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Captive spawning and embryonic development of marine ornamental purple firefish Nemateleotris decora (Randall & Allen, 1973)
Abstract
Courtship behaviour, captive breeding, embryonic and larval developments of Nemateleotris decora and its rearing with suitable live feed were described. Different age groups (60–100 mm TL) were stocked (glass aquaria, 500 L) in outdoor transparent roofed hatchery at water temperature 29 ± 1 °C for pair formation. After 6 months of rearing, 4 pairs were formed. The size of the female ranged from 60 to 90 mm and males from 90 to 100 mm. Each pair was then stocked in 250-L perspex breeding tanks in the indoor breeding unit with a photoperiod of 14 L: 10 D by a 40-W bulb suspended at 20 cm above the water surface. The environmental parameters such as temperature, salinity, dissolved oxygen and pH, NO2, NO3 and NH3 were maintained at suitable levels and monitored once in 24 h. The pairs were daily fed with cooked meat of squid, shrimp, green mussel, raw fish egg mass at 10% of their body weight in four split doses and live adult artemia (10–15 per day). The pairs began to spawn after 6 months acquisition in the breeding tanks. Each spawning consisted of 400 to 500 eggs, which were elliptical in shape with a length of 1.1 ± 0.1 mm and a maximum width of 0.4 mm. The incubation period lasted for 96 h at a water temperature of 28 ± 1 °C, and most of the time, males guarded the eggs than did females. The embryonic development and colour changes of eggs during incubation were documented. The hatching percentage ranged from 93% to 98% at water temperature 29 °C. The size of newly hatched larva varied between 1.9 ± 0.1 mm long and the mouth gape varied between 90 and 110 μm, and its behaviour was also documented. Larval rearing was carried out in 250-L rectangular tanks using phytoplanktons Nannochloropsis oculata and Chlorella salina (1:1 proportion at 1–5 × 106 cells ml− 1), along with different combinations of live micro zooplanktons: Diet I (Brachionus rotundiformis from 1 to 7 dph and Brachionus plicatilis from 8 to 18 dph), Diet II (ciliates Euplotes sp. from 1 to 7 dph and B. rotundiformis from 8 to 18 dph) and Diet III: B. plicatilis from 1 to 18 dph and Diet IV (Calaniod copepod Acartia danae nauplii from 1 to 7 dph and B. rotundiformis from 8 to 18 dph). In all diets, Artemia nauplii were fed from 19 to 40 dph to standardize its larval rearing and were provided with 24 h light. All the zooplankton species except copepods were enriched using Algamac 2000. Out of the four tested diets, Diet II showed maximum survival rate (66% ± 0.23%) followed by Diet IV (40% ± 0.40%), Diet I (10% ± 0.61%) and Diet III (3% ± 0.46%). The larvae metamorphosed to juveniles within 35 to 40 days of post-hatch (dph). This is the first scientific report on breeding of N. decora under captivity.
... For example, cyanide is used by collectors in South-East Asian countries to stun fish before capture, but it kills nontargeted marine organisms and remains a threat to the coral reef ecosystem and local food sources (Barber & Pratt 1998;Olivotto et al. 2003;Madhu & Madhu 2014). Poor handling practices, disease and stress during shipment further lead to high post-harvest mortality of marine ornamental fish (Rubec 1986;Rubec et al. 2001;Wood 2001;. ...
... Some reef fish can even change sex in both directions and are termed bidirectional hermaphrodites, as observed in some dottybacks (Pseudochromidae; Wittenrich & Munday 2005) and gobies (Gobiidae; Archambeault et al. 2016). Furthermore, determining the sex in many reef fish species is difficult, although apparent morphological features such as colour, size and body shape can be used for identifying the gender of some species (Baensch & Tamaru 2009b;Leu et al. 2010;Moorhead & Zeng 2011;Madhu et al. 2012aMadhu et al. , 2016Madhu & Madhu 2014). For instance, female bluestriped angelfish Chaetodontoplus septentrionalis have a yellow/orange pectoral fin base, while males are identified by the dark circle spot on the pectoral fin base and a larger size (Leu et al. 2010); male forktail blenny Meiacanthus atrodorsalis have a longer caudal fin edge than female (Moorhead & Zeng 2011). ...
... For species with little sexual dimorphism, their gender may become distinguishable after the bond is formed between a broodstock pair. For example, female fish usually exhibit a swollen belly prior to spawning (Leu et al. 2010;Madhu & Madhu 2014;Mies et al. 2014; Degidio et al. 2017; Majoris et al. 2018), but this feature can only be seen after females successfully reach sexual maturity. Difference in behaviour in a broodstock pair could also help differentiate the gender of individual fish. ...
Marine ornamental fish are a key component of the multimillion‐dollar marine aquarium trade industry, a controversial industry due to current heavy reliance on wild‐collected specimens. Aquaculture of marine ornamental fish is considered as a sustainable alternative, but it is still in the early stage of development. This review focuses on the current state of marine ornamental fish aquaculture, by covering topics on reef fish reproductive biology in captivity, traditional and novel live feeds, feeding regimes and visual environment in larviculture. Where possible, major differences between demersal and pelagic spawners are compared and discussed. Overall, for many ornamental fish species, natural spawning can be achieved in a captive environment without the use of hormone induction; however, sex identification and successful pairing for reef fish species could be a challenge. With the use of both traditional (rotifers and Artemia) and novel live feeds (e.g. marine copepods and ciliates), a range of breakthroughs in larval rearing of both demersal and pelagic spawning ornamental fish species have been achieved in recent years, although larval survival varies. To further improve the larval rearing success of marine ornamental fish, this review suggests that future research should focus on optimizing the use of live feed in terms of both quality and quantity, and establishment of well‐defined species‐specific larval feeding regime, as well as providing appropriate rearing condition through improved manipulation of light conditions and the ‘greenwater’ techniques in larval rearing.
... The use of live prey is still indispensable in marine finfish larviculture (Conceição et al., 2010), and it is considered a key to larval rearing success of marine ornamental fish (Anzeer et al., 2019;Chen et al., 2020;Madhu et al., 2016;Madhu and Madhu, 2014;Olivotto et al., 2006;Zeng et al., 2018). However, the species-specific larval feeding preferences and nutritional requirements often make it difficult to extrapolate successful rearing techniques from one species to another (Hamre et al., 2013;Lee et al., 2018). ...
... However, marine fish larvae in general cannot biosynthesize these essential HUFAs de novo, and must obtain them from diets (Bell et al., 2003;Glencross, 2009;Izquierdo and Koven, 2011;Sargent et al., 1999). Copepods are natural prey to marine finfish larvae (Conceição et al., 2010;Hamre et al., 2013), and the well documented positive effects of copepods in enhancing larval growth and/or survival of marine ornamental fish were often attributed to their naturally high HUFA contents (Anil et al., 2018;Bell et al., 2003;Madhu and Madhu, 2014;Olivotto et al., 2010;Olivotto et al., 2008;van der Meeren et al., 2008;Zeng et al., 2018). Similarly, in this study, a longer copepod feeding period as a result of either a latter prey shift time or adopting a gradual prey transition approach, likely had benefited the larvae by allowing them more time to obtain and accumulate higher total dietary HUFAs; this effect might subsequently lead to more robust larvae and contribute to better survival even after prey transition was completed. ...
Marine finfish hatcheries often replace small live prey with the larger traditional prey, brine shrimp Artemia, to feed the growing fish larvae. However, research on fish larviculture, including marine ornamental fish, often overlooks the importance of fine-tuning such prey transition. This study investigated the suitable time and approach for the larvae of an ornamental species, orchid dottyback Pseudochromis fridmani, to transit to the Artemia feeding phase. In experiment I, the suitable prey shift time window was estimated by abruptly feeding P. fridmani larvae with newly hatched Artemia nauplii (AN) from 5, 8, 11 or 14 days post-hatching (DPH) until 19 DPH. Although P. fridmani could ingest AN from 5 DPH, the final larval survival of 11-DPH and 14-DPH treatments were significantly higher, and it might relate to the enhanced digestive capability of older larvae. In experiment II, when prey shift began on 9, 11, or 13 DPH, the larvae were either abruptly shifted (AS) to AN feeding, or given a three-day gradual transition (GT) period of co-feeding original prey (rotifers and copepods) with AN before completing the prey switch. By 22 DPH, the prey shift strategy of GT significantly improved larval survival compared to the AS treatments; prey shift time treatments of 11-DPH and 13-DPH also reached significantly higher survival than 9-DPH treatments. However, survival of all individual treatments continued to decrease in the final stage of experiment. To further improve the prey transition success, experiment III investigated the effects of Artemia enrichment and prey shift time, by abruptly feeding larvae with either AN or enriched Artemia metanauplii (EA) from 9, 11, or 13 DPH onwards. Although the larvae fed AN were significantly larger than those fed EA, the absolute differences were small. There was a significant interaction between Artemia type and prey shift time on larval survival. The EA-11-DPH and EA-13-DPH treatments maintained steady survival post prey transition, and reached the highest mean survival of 58 ± 10%, and 55 ± 12% by 20 DPH, respectively. Moreover, while the larvae fed AN abnormally reduced prey intake over time, most larvae in EA-11-DPH and EA-13-DPH treatments still maintained high Artemia ingestion. These results suggest that dietary highly unsaturated fatty acids in enriched Artemia were crucial for larval survival of P. fridmani. Overall, this study shows that P. fridmani larvae could skip AN and directly feed on EA from 11 DPH without compromising survival or feeding performance.
... For instance, while ≥90% of freshwater ornamental fish are bred in captivity, it is estimated that 90% of marine ornamental fish are currently sourced from the ocean (Olivotto et al., 2011;Palmtag, 2017;Wabnitz et al., 2003). Indeed, destructive collection methods, such as using cyanide to stun fish, are practiced by collectors in tropical developing countries that are major suppliers for the global trade, impacting the health of coral reefs ecosystem (Barber and Pratt, 1998;Madhu and Madhu, 2014;Olivotto et al., 2003;Rubec, 1988). Aquaculture of marine ornamental fish is therefore a critical solution to reduce fishing pressure on wild stocks (Chen et al., 2020;Madhu et al., 2016;Moorhead and Zeng, 2011;Palmtag, 2017;Sadovy et al., 2001). ...
... In addition to being costeffective for hatcheries to produce in large quantity, rotifers have a slow and smooth swimming motion making them relatively easy targets for early larvae with limited swimming ability to hunt (Conceição et al., 2010;Lubzens et al., 2001). However, rotifers (approximate length range = 110-250 μm) can be too big for larvae with small mouth gape to ingest (Leu et al., 2015(Leu et al., , 2009Madhu et al., 2016;Madhu and Madhu, 2014), and can fail to elicit larval feeding response for some species of marine ornamental fish (Saravanan et al., 2013). In contrast, copepod nauplii can be as small as 60-70 μm (McKinnon et al., 2003), and copepods also have a more dynamic "stop-and-go" swimming motion that may be effective in eliciting the larval predatory response (Degidio et al., 2018;Saravanan et al., 2013). ...
Captive breeding of marine ornamental fish is considered as a sustainable alternative to the current practice of fishing the wild stocks to supply the marine aquarium trade. However, efficient larviculture remains the biggest bottleneck, as many marine ornamentals suffered total mortality or only have extremely low survival at early larval stage. This study investigated the optimal conditions for the rearing of early larvae of a valuable ornamental fish, the orchid dottyback Pseudochromis fridmani, in terms of density and combination of live prey, as well as the application of the “greenwater” technique. In the first experiment, larvae were reared in clearwater and fed rotifers at 2, 5, 15, and 40 mL⁻¹. Although there was no significant difference in larval survival among treatments on 8 days post-hatching (DPH), the larvae fed higher rotifer densities (15 and 40 rotifers mL⁻¹) had significantly better growth. In the second experiment, by 8 DPH, a significant interaction between rearing condition (clearwater vs. greenwater) and live prey combination (rotifers only vs co-feed rotifers and copepods) on larval survival was detected, and the mean survival of larvae co-fed rotifers and copepods in clearwater (18%) was significantly lower than the other treatments (45–64%). Moreover, larvae reared in greenwater, or co-fed rotifers and copepods, grew significantly larger than those reared in clearwater, or fed rotifers only, respectively. In the third experiment, larval survival increased with increasing cell density of Nannochloropsis paste (NAN) used to make greenwater (0–3.40 × 10⁶ NAN cells mL⁻¹). The larval survival of the highest algae density treatment was the highest on 8 DPH (72 ± 8%), and it was significantly higher than those reared in the treatments of 1.13 × 10⁶ or 0 NAN cells mL⁻¹, but not significantly different from that of 2.27 × 10⁶ cells mL⁻¹ treatment. Overall, the results of this study suggest that co-feeding early P. fridmani larvae with rotifers and copepods, with the complementary use of greenwater comprising of ≥ 2.27 × 10⁶ NAN cells mL⁻¹, can enhance larval survival, growth and development. However, when the algal cell density is below this threshold, using such a co-feeding strategy may compromise the survival of P. fridmani larvae. The results of this study highlighted the importance of optimizing the application of live prey and greenwater for improving the survival of marine fish larvae.
... coioides Hamilton) (Liao, Su & Chang 2001), cobia (Rachycentron canadum Linnaeus) (Holt, Faulk & Schwarz 2007), sea bass (Dicentrarchus labrax Linnaeus) and the gilthead sea bream (Sparus aurata Linnaeus) (Sorgeloos, Dehasque, Dhert & Lavens 1995), large scale production of ornamental fish is rare. Despite successful breeding and rearing of some ornamental fish in display aquaria and laboratories (e.g., Leu et al. 2010Leu et al. , 2012Saravanan, Vijayanand, Vagelli, Murugan, Shanker, Rajagopal & Balasubramanian 2013;Madhu & Madhu 2014), they have been largely limited to small and experimental scales. ...
... Traditionally, most food fish larvae are raised in ponds by adding rotifers, Artemia nauplii, and copepods as prey (Liao et al. 2001;Ma, Qin, Hutchinson & Chen 2013;Shan & Lin 2014). Ornamental fish with demersal eggs or mouth/pouch brooding habits and relatively large larvae can also be successfully cultured using copepods and super small rotifers (SS-type rotifers) (Ogawa & Brown 2001;Olivotto, Cardinali, Barbaresi, Maradonna & Carnevali 2003;Wabnitz, Taylor, Green & Razak 2003;Olivotto, Gaiot, Holste, Tulli, Cardinaletti, Piccinetti, Gioacchini & Carnevali 2012;Madhu & Madhu 2014). However, whether the sizes of prey suitable for ornamental fish species such as angelfish (Pomacanthidae) are suitable for other species is debatable, given the mouth gape limitations of the larvae, i.e. about 150~200 lm (Leu et al. 2009(Leu et al. , 2010. ...
Coral reef fish are collected from the wild and exhibited in aquaria worldwide. Some of the fish spawn in captivity; however, the eggs are usually neglected. In this study, we collected the eggs spawned naturally in the exhibit tanks, hatched and cultured them indoor in 2000-L fibreglass tanks (initial density = 18 000 egg tank−1). We applied an inorganic fertilization method commonly used in freshwater fish culture in raising these coral reef fish larvae. We maintained inorganic phosphorus concentration at 100 μg P L−1 and inorganic nitrogen at 700 μg N L−1 daily in the fertilized group (n = 4), while the control tanks (n = 4) were fed with rotifers (10 ind mL−1). Chlorophyll a at particle sizes of both 0.45–20 μm and >20 μm, as well as NH3-N, NO3-N, and PO4-P concentrations were significantly higher in the fertilized group than the control. Zooplankton in the size groups of 10–50 μm (mainly flagellates) and 50–100 μm (mainly ciliates) were abundant (about 10~60 ind mL−1) during 3–7 days in fertilized tanks. The average larval fish survival rate at 21 day after hatch in fertilized group was consistently higher than the control in two trials. The experiments demonstrated that the inorganic fertilization approach can be successfully adapted for coral reef fish culture in an aquarium to achieve sustainable exhibits.
... In general, most information on reproductive biology and the embryonic and larval developmental features of P. fridmani is reported by aquarium hobbyists [10,28]. Compared with the scientific data on the embryonic and larval development of other marine ornamental fishes [20,[29][30][31], hobbyists' documentation on P. fridmani lacks detailed morphological description as well as high-quality photographic detail at important developmental stages. ...
Aquaculture of marine ornamental fish could potentially reduce the fishing pressure on wild stocks by the global aquarium trade, but its expansion is often constrained by the limited understanding on the biology and early life history of candidate species. The orchid dottyback Pseudochromis fridmani is a valuable and popular marine ornamental fish, but scientific reports on its baseline biology, especially the egg filial cannibalistic behaviour, are scarce. The present study documented key aspects of reproductive biology and early ontogeny of P. fridmani in captivity, including reproductive behaviour, patterns of spawning and filial cannibalism throughout a 12-month period by seven pairs of brood fish, as well as the embryonic and larval development. The results showed that the captive spawning of the broodstock pairs generally occurred every 5–11 days, most commonly every 6–8 days, throughout a year. Despite feeding the brood fish to satiation throughout the data collection period, the average monthly rate of egg filial cannibalism reached 55 ± 37%, but the cannibalism frequency appeared to be pair-specific. The egg incubation duration was approximately 96 h at 27 ± 1 °C, and the development of embryos from cleavage, blastula, gastrula, and segmentation to the pharyngula stage is herein described in detail. The newly hatched P. fridmani larvae possessed important structures and organs for first feeding, including pigmented eyes, developed jaws, and a straight-tube gut. The 0 to 14 days post-hatching (DPH) period appeared to be an important larval stage, as P. fridmani larvae were observed to complete major changes in morphology, gut development, and phototactic behaviour by 14 DPH. Under the culture conditions of this study, the earliest transition to the juvenile stage was observed on 31 DPH, and the majority of fish became juveniles by 56 DPH. The results of this study inform baseline aquaculture production protocols and direct future research, particularly to reduce filial cannibalism through broodstock management and to improve larval culture through supporting the early ontogenetic development of P. fridmani. Additionally, these findings form a foundation for further studying the biology and ecology of P. fridmani in the wild.
... Number of eggs spawned by females in present study fluctuated widely from 500 to 4,200 eggs per spawn and averaged 1,837 ± 1,197 eggs, which is comparatively higher than other demersal spawning ornamental species previously reported, including the Gobidd fish Priolepis nocturna (268 to 3,121 eggs) [17], the folktail blenny Meiacanthus atrodorsalis (315 to 2,575 eggs) [15], and the purple firefish Nemateleotris decora (400 to 500 eggs) [18]. The egg incubation period was found to be between 204-207 hours or around 8.5 days at 27 ± 1 o C, which is slightly longer than 7 days reported by Olivoto et al (2010) at 28 o C. The difference is most likely due to lower water temperature during the incubation in this study since temperature is well known to exert decisively influence on embryonic development rate of fish [19]. ...
This study aims to describe aspects of reproductive behavior and larval development for the striped blenny, Meiacanthus grammistes. Altogether 8 broodstock fish (8.5 cm to 10 cm) were maintained in two 400 l tanks. The first spawning occurred 45 days in one tank and 65 days in another tank after fish acquisition. Egg clutches were only found attached to inside walls of the 50 mm capped PVC pipes with a single 25 mm reduce entry hole while the male took full responsibility for egg care. The fish spawned routinely every 8–10 days in both tanks throughout experimental period. The fecundity ranged from 500–4,200 eggs per spawning with an average of 1837 ± 1197 eggs/clutch. Newly extruded eggs were spherical and incubation period lasted 203–207 h at 27 ± 1oC. Newly hatched larvae measured 3.11 ± 0.14 mm in standard length (SL) and 0.87 ± 0.08 mm in body depth (BD) with average mouth-gape height and width at 272.42 ± 61.03 µm and 187.50 ± 36.46 µm, respectively. Under such a feeding regime, most of larvae had settled out water column onto the bottom around 23 DPH but not yet displayed the full colouration pattern of adults. In period of 24 to 29 DPH, the colouration pattern developed with alternating black and yellow stripes running through the entire length of body and the newly settled juvenile measured 12.91 ± 0.35 mm in SL and 3.36 ± 0.12 mm in BD around 30 DPH.
... Ciliates are a group of micrometre-sized protists that show great potential for feeding small-mouthed reef fish larvae, such as cleaner goby (Gobiosoma evelynae), purple fire-fish ( Nemateleotris decora) and blue-striped angelfi sh (Chaetodontoplus septentrionalis) (Olivotto et al., 2005;Madhu and Madhu, 2014;Leu et al., 2015). Ciliate production relies on the suspending organic matters and bacteria as their dietary resources, which makes their cultivation relatively easy. ...
... These investigations made CMFRI have resulted in the development of hatchery technology for 21 species of marine ornamental fishes such as clown fishes Amphiprion percula(True percula/ clown anemone fish);A. ocellaris (Common Clown/False clown aenemonefish); A. sandaracinos (Yellow Skunk Clown); A. frenatus (Tomato clown), A. clarkii (Clark's anemone fish), A. sebae (Sebae clown) A. periderarion(Pink anemone fish ) A. ephippium ( 2007; Madhu et al., 2008, Madhu and Rema Madhu, 2014, Madhu et al.,2016. It is well accepted that the trade developed from tank reared fish and other ornamentals is the final solution for a long term sustainable trade. ...
The marine ornamental fish trade is a sunrise industry in aquaculture and has become a growing industry worldwide. As a result, the trade of marine ornamentals has been expanding in recent years and has grown into a multimillion-dollar enterprise mainly due to the emergence of modern aquarium gadgets and technologies for setting and maintenance of miniature reef aquaria. Since the marine ornamental trade is operated throughout the tropics, the global marine ornamental trade is estimated at US$ 200-330 million. Since India is endowed with a vast resource potential of marine ornamentals distributed in the coral seas and rocky coasts with patchy coral formations and the increasing the demand in the domestic trade, it appears very much lucrative for India to venture into this industry. But it is a multi stakeholder industry ranging from specimen collectors, culturists, wholesalers, transhippers, retailers, hobbyists, researchers, government resource managers and conservators, and hence involves a series of issues to be addressed and policies to be formulated for developing and expanding a sustainable trade. Nearly 98% of the marine ornamental fishes marketed are wild collected from coral reefs of tropical countries. This has been threatening the long term sustainability of the trade due to indiscriminate exploitation of coral reef areas. The only alternative for the sustainable trade is the captive production which involved broodstock development, breeding, live feed culture, larviculture, growout, aquarium technology, diseases, packing and transportation, etc. The Central Marine Fisheries Research Institute (CMFRI) has been focusing on this vital aspect of this low volume and high-value industry for the
past few years.
... Locally, where populations have been overharvested, ecological imbalances have been created due to selective fisheries focused on a few target species, sexes, or ages with higher market values (Domínguez and Botella, 2014). In some source locales, destructive collection methods such as dynamiting and the use of cyanide to stun tropical fish also harms coral reefs, non-target species, and the marine ecosystem; ultimately threatening the human food source (Madhu and Madhu, 2014). Concern for the health of coral reefs caused by real or perceived threats from fishing for the marine aquarium trade has resulted in the shutdown of the fishery in certain high-profile source locales. ...
An average of 7.6 M individual fishes, representing 1.8 K species from 125 distinct fish families, are imported into the U.S. annually for the marine aquarium trade. While many wild-caught species are traded annually, there are only ~39 commercial aquaculture businesses in the U.S. (2020), and 96 species commercially available as aquacultured. This study presents a data-driven framework to empower the selection of species to target for aquaculture research and development. The framework is based on species-specific data for 105 of the top 130 species imported into the U.S., including market characteristics (aquarium suitability, number of imports, retail price), aquaculture practicality (demersal/pelagic spawning strategy, pelagic larval duration, size at hatch), and conservation assessment (aquacultured status, ecological niche, geographic distribution, and mid-depth). A principal component analysis revealed that fish species which feature life history characteristics conducive to practical aquaculture efforts also either 1) demonstrate favorable market characteristics, or 2) are vulnerable to overfishing and thus merit the effort from a conservation perspective. Conversely, fish species whose life history characteristics render them challenging to aquaculture also either 1) demonstrate less favorable market characteristics, or 2) also demonstrate life history characteristics that equip them with resiliency to overfishing and thus may best be prioritized for wild collection under sound fisheries management.
... Most importantly, ciliates are known for their tiny cell size (20-60 µm), which is particularly favorable for small-mouthed larvae (Hill et al., 2020). Indeed, ciliate-based diets have been acknowledged to successfully sustain larvae rearing of several marine ornamental or edible fish species (Nagano et al., 2000;Rhodes and Phelps, 2008;Madhu and Madhu, 2014;Leu et al., 2015). On the other hand, the use of bacteriovorous ciliates for pathogen removal has recently emerged. ...
In marine larviculture, farmed larvae mainly rely on the alimentation of a group of small-sized phytoplankton and zooplankton referred to as live feed. Under the diversifying demands of human consumption and ornamental aquarium industry, new species of live feed and their innovative production methods are essential focuses for sustainable larviculture of many emerging fish and invertebrate species. The selection of proper live feed for larval feeding is based on several parameters, such as size, morphology, nutritional value, stock density and growth rate. This review aims to highlight the biological characteristics, production approach, common larviculture applications as well as recent innovations in the aquaculture technology of live feed organisms (microalgae, ciliated protists, rotifer, Artemia, copepod and others).
... Compared to the research conducted on marine foodfish species (Cahu and Zambonino Infante, 2001;Faulk and Holt, 2009;Holt et al., 2011;Ma et al., 2015;Ma et al., 2014b;Thompson et al., 2019), weaning marine ornamental fish larvae onto formulated feed is much less explored. Breeding marine ornamental fish in captivity to meet the demand of the aquarium trade, is considered as a sustainable solution to reduce the negative environmental impacts associated with collection of live fish from coral reefs, which is the currently the main source of fish supply for the marine aquarium trade (Barber and Pratt, 1998;Chen et al., 2020;Madhu and Madhu, 2014;Moorhead and Zeng, 2010;Palmtag, 2017;Sadovy et al., 2001). In order to overcome the major bottleneck of larviculture, most studies on marine ornamental fish aquaculture have focused on the live prey rearing phase (Chen et al., 2020;Holt, 2003;Moorhead and Zeng, 2010). ...
Although live prey remain essential for most marine finfish larviculture, the larvae or young juveniles are ultimately weaned onto formulated feeds at foodfish and ornamental fish hatcheries. Understanding the development of larval digestive capabilities is crucial for optimizing weaning success. The present study used the digestive system ontogeny to interpret the effects of different weaning times on larval rearing of orchid dottyback Pseudochromis fridmani, a marine ornamental fish species. The study documented the ontogenetic digestive system development of P. fridmani larvae from hatching to 40 days post-hatching (DPH). The histological analysis showed that as a demersal spawning species, the newly hatched P. fridmani larvae possessed advanced gut development which allowed the onset of exogenous feeding soon after hatching. Most major larval gut morphological changes were completed by 13 DPH; however, the stomach and gastric glands were first observed between 32 and 36 DPH. At this stage, P. fridmani larvae were expected to acquire substantially improved digestive capabilities, and were likely capable of digesting formulated feed. In the subsequent experiment, P. fridmani larvae were weaned onto formulated feed from 20, 23, 26, 29, or 32 DPH over a three-day period of co-feeding with enriched Artemia; the control group were exclusively fed enriched Artemia until the end of experiment. The timing of weaning significantly affected the larval growth and pigmentation development rather than survival (mean: 44–64%). P. fridmani larvae weaned later tended to grow larger, and the control group grew significantly larger in length than all weaning treatments (p < 0.05). Interestingly, at the end of the experiment (40 DPH), none of larvae from the control obtained adult-type pigmentation despite their larger size. In contrast, the introduction of weaning formulated feed appeared to stimulate pigmentation development in P. fridmani individuals with a clear trend of higher pigmentation completion by 40 DPH (mean: 62–97%) with earlier weaning. Overall, this study demonstrated that P. fridmani larvae could be weaned onto formulated feed from as early as 20 DPH, before the stomach and gastric glands were fully developed; indeed, the timing of adult-type pigmentation change in P. fridmani was also advanced by the introduction of the weaning diet.
... Euplotes sp. has been evaluated as feeding supplements for copepods and various first feed in many fish larvae. As tabulated in Table 4, the inclusion of Euplotes and Brachionus rotundiformis resulted in more than 50% survival in firefish and shark nose goby larviculture compared with the group fed B. rotundiformis only (Madhu & Madhu, 2014;Olivotto et al., 2005). The presence of Euplotus labelled with fluorescent microspheres in the larvae gut of surgeonfish, Paracanthurus hepatus, and grouper, Epinephelus septemfasciatus, during the experimental feeding trial confirmed that this fish could digest Euplotes in the early stage of feeding activity . ...
Aquaculture is considered one of the world's fastest-growing
food production industries. It provides one of the most environmentally friendly sources of edible protein. The rapid expansion of aquaculture has occurred in response to a huge increase in world population and the corresponding demand for food, highlighting a path towards
intensive sustainable products and resource efficiency. Improved process efficiency
has fuelled aquaculture expansion, which involves addressing operational performance,
particularly on nutrition and health of farmed fish, as well as a trend towards
reaching natural or organic certification. Although there is ample evidence to support
the use of microorganisms, including algae, bacteria, fungi, archaea, protozoa and viruses,
their use in aquaculture nutrition is still limited in natural medicine development
and therapies. Notably, various applications of microorganisms feed have a significant
impact on aquatic animal health and husbandry. However, there is a need to discuss
various roles of microorganisms used in aquaculture feed extensively. This review
discusses the potential of microorganisms and their role as value added aquaculture
feed, which could offer aquaculture and feed producers considerable benefits.
... Interestingly, Gobiidae were also among the most CB families with 44 species but their occurrence was limited in scientific literature (eight species, Fig. 5). With the exception of Microdesmidae (no recorded as CB but one species studied by academists, Madhu & Madhu 2014), there was always a greater number of CB species than species studied by academic researchers. This trend was particularly true for Gobiidae because they were also among the most studies CB families with 44 species, but their occurrence was limited in scientific literature (eight species, Fig. 5). ...
The marine ornamental fish trade is expanding and still largely relies on wild fish from tropical coral reef ecosystems. There are unknowns in the wild harvest so that the sustainability of marine ornamental fish trade can therefore be questioned with aquaculture being perceived as a responsible alternative for the procurement of these ornamental marine fish. However, there are still many technical constraints that hinder its development. These blocks require additional coordination with the outcome being an accelerated development of ornamental marine fish production. The main objective of this review was to better identify, understand and discuss the role and the impacts of academic research in the production of marine ornamental fish through qualitative and quantitative approaches. To do so, 222 selected scientific publications (including peer‐reviewed articles, conferences articles, thesis and reports) from the literature available to date were analysed and outcomes were framed in perspective of the total number of captive‐bred species. Results of the meta‐analyses indicate that academic research has led to significant advances in the breeding of some of the more difficult to breed species. While it has a leading role in conservation, its advance of techniques still lags behind private companies and hobbyists. Partnerships promoting synergistic activities between academic research institutes and the private sector (aquaculture farms and public aquariums) are important to optimize future ornamental marine fish production.
... Till date, 90 species of marine ornamental fishes, 30 of these pomacentrids, have been bred in captivity but the attempts for mass scale production of many species have not yet been standardised. Among those, the early stages in the life of only 15% of pomacentrid species have been described to any level and the quality and extent of existing descriptions are also not uniform (Danilowicz and Brown, 1992;Murphy et al., 2007;Moorhead and Zeng, 2010;Setu et al., 2010;Madhu and Rema, 2014). ...
As the demand for marine ornamental fish is ever increasing, the industry largely relies on collections from natural habitat due to insufficient breeding and seed production technologies. Fishes of the family Pomacentridae are popular in marine aquaria throughout the world. Among these, damsel fishes of the genus Dascyllus has high demand and are mostly collected from the wild. The present study forms the first-ever report on successful breeding and larval development of Cloudy Damsel (Dascyllus carneus Fischer, 1885). Though there are a few reports on breeding of other species of Dascyllus, there has been no report on the complete larval development of any of the species in this genus. This forms the first description of early larval development of a Dascyllus species. Using the copepod Parvocalanus crassirostris as first feed the larval rearing was done. Successful breeding and larval development were achieved from the wild-caught broodstock of D. carneus at Vizhinjam Research Centre of ICAR-CMFRI, India. Brood stock from the wild took 4 months to spawn, laid 6500-10,500 eggs per spawning and hatching rate ranged from 90.6 to 98.81%. Newly hatched larvae were the smallest among all the reported larvae of pomacentrid fishes and measured 1.95 ± 0.14 mm in total length. Yolk reserve was completely absorbed within 72 h of hatching. Preflexion stage is from 4 to 10 dph, flexion stage is from 11 to 12 dph and postflexion period is 13-15 dph. Larvae accepted only copepod naupliar stages as first feed and calanoid copepod P. crassirostris alone was fed until 25 dph. Larvae settled from planktonic stage in 22-23 days and all the larvae metamorphosed into juveniles by 50 dph. The egg development, larval development and larval pigmentation up to 50 dph has been described. The feeding protocols and feed size preference in relation to their age or mouth gape, the gut contents and mouth gape of the larvae caught from a feed trial with surplus copepods of all stages were analysed at regular intervals. Larvae preferred larger stages of copepods in later stages of their development. Finally larval feeding protocols were modified accordingly and better survival was observed. A final feeding regime has been developed and a strategy for the consistent hatchery production of this species was achieved. Different stages of copepod P. crassirostris were used till the settlement of planktonic stage of larvae and Artemia nauplii were used from 25 dph. The larvae were completely weaned to artificial diet from 50 dph.
... Till date, 90 species of marine ornamental fishes, 30 of these pomacentrids, have been bred in captivity but the attempts for mass scale production of many species have not yet been standardised. Among those, the early stages in the life of only 15% of pomacentrid species have been described to any level and the quality and extent of existing descriptions are also not uniform (Danilowicz and Brown, 1992;Murphy et al., 2007;Moorhead and Zeng, 2010;Setu et al., 2010;Madhu and Rema, 2014). ...
... Lythrypnus dalli larvae at their first feeding stage (Archambeault et al., 2016;Madhu & Madhu, 2014;Wittenrich et al., 2007). The gape size of the mouth of newly hatched I. ornatus is approximately 235.21-298.96 ...
Natural spawning, early development and larviculture of the ornate goby Istigobius ornatus in captivity were studied for the first time. I. ornatus spawned 46 times from 31 October 2013 to 31 October 2014. Fecundity ranged from 246 to 10,214 eggs per clutch, with an average hatching rate of 77.8% ± 9.9% (M ± SEM). Fertilized eggs (1.31-1.54 × 0.46-0.50 mm in diameter) were adhesive demersal and oval-shaped. Embryonic development lasted 84 hr at 27.5 ± 0.5°C. Newly hatched larvae [2.12 ± 0.04 mm in total length (TL)] transformed to the juvenile stage completely when TL was 7.79 mm. Effects of different water temperatures (24, 28 and 32°C) and salinities (10, 15, 20, 25, 30, 35 and 40 g/L) on per cent survivals (%) and survival activity indices (SAIs) were tested. Survival was not significantly different under different temperatures; SAIs was significantly higher at 28°C. Larvae showed the significantly higher survival and SAIs at salinities 10-30 g/L than at 35 and 40 g/L. Effect of different prey densities on survival was significantly higher in 7 days post hatch larvae fed 20 and 30 rotifers/ml. These findings could guide future programs in captive breeding technology development and commercial production of other marine ornamental gobies.
... All the demersal species display parental care until the embryos hatch. Typical examples are damselfish, clownfishes, dottybacks, gobies and blennies (Brons, 1996 Olivotto et al., 2011a,b;Madhu and Madhu, 2014;. ...
... Several species have been studied and tested on different marine ornamental species including demersal and pelagic spawners. In demersal spawners, such as clownfishes, firefish and comets, calanoid copepod administration (Centropages typicus, Acartia tonsa, A. danae, C. hamatus) was able to significantly improve both survival and growth rates compared to larvae fed on a standard diet of rotifers and Artemia (Holt, 2003;Olivotto et al., 2008aOlivotto et al., , 2012Madhu & Madhu, 2014). ...
The early development and growth of marine species largely relies on the capture, digestion and assimilation of adequate live food. The type of prey available to aquarists and professional producers is certainly limited, but there is still a range of possibilities in the selection of prey suitable for a variety of species. The most widely used preys in the rearing of larvae are rotifers and Artemia spp. These preys are not ideal, especially from a nutritional point of view. In spite of that, reasonably good results can be attained in the early rearing of a fairly wide variety of species when those prey are properly enriched. However, improvements can be achieved by supplying copepods as an alternative food source for the larvae. Currently, several copepod species can be successfully cultivated. Their incorporation into the feeding scheme of larvae, as unique prey or supplementary to the traditional prey, is advantageous due to their higher nutritional quality and the wider range of sizes available for different stages of larval development.
... All the demersal species display parental care until the embryos hatch. Typical examples are damselfish, clownfishes, dottybacks, gobies and blennies (Brons, 1996 Olivotto et al., 2011a,b;Madhu and Madhu, 2014;. ...
... The ability of diseases resistance makes it a popular species of reef aquariums. The studies about the elegant firefish were limited, except for the spawning and developmental biological study (Madhu & Madhu, 2014). In this study, we determined the complete mitochondrial DNA of N. decora (GenBank accession number: KT284932), which would provide a useful reference for studying conservation genetics, phylogenetic analysis and comparative mitogenomics. ...
We determined the mitochondrial genome (mitogenome) sequence of Nemateleotris decora by using a long polymerase chain reaction (PCR) method and next-generation sequence (NGS) technology. The total length of N. decora mitogenome is 16 502 bp, consisting of 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs genes, and a non-coding control region. The overall base composition of N. decora is 25.22% for A, 25.90% for T, 30.69% for G, and 18.19% for C. Our results showed the complete mitogenome is a good marker for the phylogenetic study.
The marine ornamental fish trading industry is an ever-expanding one, as indicated by its bolstering statistics, which amount to about US$ 300 million. Although the trade is booming, the natural habitats that foster these fishes, such as coral reefs, are steadily declining. One of the reasons for this is the overdependency of the industry on wild-caught fishes. To surpass this, the Central Marine Fisheries Research Institute (CMFRI) has developed hatchery technology for breeding marine ornamental fishes such as seahorses, clownfishes, damsels, and serranids. It began with the breeding of Hippocampus kuda. This progressed to breeding clownfishes such as Amphiprion chrysogaster, A. ocellaris, A. nigripes, A. peridarion, and A. ephippium and Premnas biaculeatus. Damsel fishes that were bred successfully include Chrysiptera cyanea, C. hemicyanea Neopomacentrus cyanomos, N. nemurus, and Dascyllus carneus. The recirculating aquaculture system (RAS) designed in the Vizhinjam Regional Centre of CMFRI is being used for broodstock development of serranids, tangs, squirrel fishes, and soldier fishes. A standard method was developed for captive breeding and hatchery rearing of anthias Pseudanthias marcia and P. squamipinnis in an advanced indigenous RAS system. The present article provides a bird’s eye view of the important research work done in India concerning marine ornamental fish breeding and reviews important breeding work carried out at Vizhinjam Regional Centre of CMFRI.
In the present study, protozoa was cultured in different salinity water (10%, 20% and 30%) to determine the optimum salinity level required for the culturing. We examined the densities of protozoa and the ciliates Euplotes spp. in a general culture and Euplotes encysticus Yonezawa in a separate monoculture. Various species of protozoa were observed in the culture water, with a peak density of 30,000–40,000 cells ml–1 on day 4. The density of Euplotes spp. in the culture water increased with elapsed days, peaking on day 3. One-way analysis of variance showed a significant difference in the densities on day 3, and post-hoc Tukey–Kramer test results showed that the density at 10% was significantly higher than that at 30%. The E. encysticus monoculture peaked at 5000–6000 cells ml–1, but there was no significant difference between the salinity levels. Although our results are not definitive, the lower salinity level appeared most suitable for culturing protozoa. The ciliated protozoa Euplotes spp. in the current study were smaller than 100 µm, and they may be suitable size as live feed as starter diet for marine fish larvae with small mouth openings
The marine ornamental fish trade generates over USD1.5 billion annually and continues to increase. However, only 35 fish species are thought to be commercially produced for sale currently, a small proportion of the 1800 species recorded within this trade. The limiting factor in marine ornamental fish production is the requirement for appropriately sized live food as a first feed. This is due to the small gape size of many fish species of interest to the trade. The need for suitable live feeds has therefore caused a bottleneck in the production of marine ornamental fish species and developments are needed to allow an expansion of this culture industry. This review considers the current usage of live feeds, including Artemia, rotifers, copepods, and ciliates and discusses the advantages and disadvantages of each when used to culture marine ornamental fish. Whilst success has been seen with these feeds for several commercially important marine ornamental fish species, the current lack of appropriately sized live feed items for higher value species, such as dwarf angelfish, remains a problem for the industry. Live feeds currently used often exceed the gape size of such species at the onset of exogenous feeding, resulting in limited commercial success. Future developments focussing on novel and existing live feeds used within the industry for these valuable species are explored. These developments will enable aquaculture, rather than the exploitation of wild populations, to meet future demand and will encourage progress in the aquaculture of marine ornamental fishes.
High mortality is common when culturing most marine fish larvae, especially during the transition from endogenous to exogenous feeding. In aquaculture, many species of marine fish are not able to survive when only fed enriched rotifers and Artemia spp. nauplii. Ciliates are a potential alternative live food organism for first‐feeding larvae, because they can grow to high population densities, accept inert diets, and are natural prey organisms of marine fish larvae. The range of culture parameters to optimize population growth of the ciliate Euplotes sp. are unknown. Five experiments were conducted to determine the effects of food concentration and abiotic factors including salinity, aeration rate, temperature and photoperiod on population growth of the ciliate Euplotes sp. Results indicated the optimal ranges for population growth of Euplotes sp. was a temperature between 26 and 32°C, salinities from 20 and 35 g/L, food (Protein Selco®) concentrations of 250 and 500 mg/million ciliates, absence of or low aeration (8.5 cm3/min) and the photoperiod 0L:24D. Euplotes sp. can tolerate high ammonia and very low dissolved oxygen concentrations, and population growth can occur in these conditions for at least 7 days.
Zebrasoma flavescens (Bennett) aquaculture is limited by high mortality during first feeding. Photoperiod, light intensity, turbidity and prey density are culture parameters that have been shown to affect feed incidence and survival in some food fish species, offering a logical starting point to improve first feeding in Z. flavescens. This study aimed to determine the effect of photoperiod, light intensity, turbidity and prey density on feed incidence and survival in larval yellow tang age 3 DPH to 5 DPH (days post hatch). Larvae were reared in four photoperiods (24L:0D, 16L:8D, 12L:12D, 0L:24D), four light intensities (1,500, 3,000, 4,500 and 6,500 lx), three turbidity ranges (0 cells/ml, 100,000–200,000 cells/ml and 400,000–600,000 cells/ml) and four prey densities (1, 3, 6 and 9 per mL). Photoperiod at 16L:8D and 12L:12D significantly increased feed incidence; 16L:8D significantly increased survival. Light intensities at 3,000 and 4,500 lx significantly increased feed incidence. Larvae reared in 400,000–600,000 cells/ml fed and survived significantly better than those in clear water. Larvae in 1 per mL fed and survived significantly less than those fed at 6 per mL.
The selection and environmental conditioning of broodstock are fundamental to assure the success of marine ornamental species cultivation. In this chapter we present some important topics for the planning, design and operation of systems and infrastructures for broodstock management and reproduction, including details regarding the biological requirements of cultivated species, broodstock infrastructures and operational costs. Basic concepts adequate for the maintenance of marine ornamental organisms of different taxonomic groups are also presented. However, producers should augment the biological knowledge about the species to be cultivated, in order to adapt and develop the concepts presented here.
Demersal spawning and mouthbrooding species comprise more than 70% of the production of marine ornamental fish. Apart from clownfish, there are several families of demersal spawners that are cultured for the ornamental trade, including gobies, blennies, dottybacks, damselfish and others. These species are characterized by producing eggs that are deposited on a substrate. The eggs are tightly packed together and may be adhered to the substrate or simply laying on it. Most ornamental demersal spawners display parental care during embryonic development and this feature is critical for successful hatching. Mouthbrooders, on the other hand, orally incubate the embryos before hatching. Newly hatched larvae of demersal spawners and mouthbrooders typically have very little yolk and are able to feed immediately after hatching. Live feeds such as rotifers and brine shrimp nauplii are frequently offered, but additional food sources including wild zooplankton, copepods and ciliates can be essential for successful mass production of some species.
Reproductive behaviour, captive breeding, embryonic, larval development and suitable live feed for Pseudochromis dilectus were found out. Fishes ranging in total length 80–120 mm (male) and 70–80 mm (female) were reared in FRP tank (1000-L) for six months to develop pairs. The pairs laid ball-shaped egg mass (25 to 35 mm diameter) which consisted of 400 to 500 spherical eggs/pair/spawning (n = 18).The size of the individual egg varied between 1743 and 1919 μm and all the eggs were interconnected by fine sticky threads. The egg ball was white or transparent on the first and second day, black on 3rd day and silvery on 4th day of incubation. The hatching rate varied between 91 and 95%, and the peak hatching took place under complete darkness on completion of 96 h incubation. Total length of the newly hatched larvae varied between 5.1 and 5.3 mm with mouth gape 150 to 160 μm. First feeding started at 10 to 12 h after post hatch. The study concluded that Euplotes sp. (0 to 5 dph), enriched rotifer (6–15 dph) and microalgae enriched Diaphanosoma celebensis (16 to 30 dph) can be used as effective feed for high survival of larvae of P. dilectus. On 20 dph the metamorphosis initiated and became juvenile stage at 30 dph (82%). At 45 dph, all the larvae transformed to juvenile and shifted from pelagic to epibenthic in the aquarium with denser body having reddish colouration.
Statement of relevance
Pseudochromis dilectus (Family: Pseudochromidae) is a species of keen interest in marine aquarium trade and has distribution in the Western and Central Indian Ocean to Sri Lanka. As its males are colourful than the female, males are selectively exploited from the nature for aquarium trade which is also causing threat to natural population thereby reducing its availability. Hence captive production is a potential solution for reducing pressure on the natural stocks. However no scientific studies were conducted in P. dilectus with an objective to captive breeding. Hence the present study was aimed to generate baseline information on its reproductive behaviour, spawning, egg morphology, embryonic and larval development of P. dilectus and also to find out suitable live feed for higher survivability of larvae, their metamorphosis and juvenile production under captive conditions with a view to develop a reliable captive breeding and rearing techniques for its mass scale production.
Gonadal sex differetiation through histological analysis and social structure were investigated in anemone fish Amphiprion percula occuring in Andaman and Nicobar islands. Field observation in different locations of Bay island showed that this species is always seen in association with their host sea anemones Heteractis magnifica H. crispa and Stichodactyla gigantea as small social groups that include an adult pair and one to three juveniles (sub adults) and the largest fish is usually the female and the next largest one is the functional male. Considerable size difference consistently appeared between the sexually active female and male, and noticed that a hierarchy exists in which the female is the dominant individual in a social group. Histological examination of gonads indicated that all juveniles start their life as male and subsequently changes into females as they reach larger sizes and mature. Based on the histological observation, the gonad was categorized into seven phases: immature phase, pre-ripe male phase, ripe male phase, transitional phase, pre-ripe female phase, ripe female phase-I and ripe female phase-II. All the juveniles had ambosexual gonads with testicular and ovarian tissues. Fishes in ripe female phase-II had ovaries with many fully grown yolky oocytes and vitellogenic oocytes, which were absent in ripe female phase-I, and characterized by the presence of many perivitellogenic oocytes and an ovarian cavity but have no testicular tissue. The study confirmed the sex reversal in A. percula from male to female (protandrous hermaphroditism). The field study supported that social structure plays an important role in its sex change.
The broodstock development, breeding, embryonic development and larviculture of Premnas biaculeatus under different feeding and envrionmental conditions are reported for the first time. The influence of enriched rotifer (Brachionus rotundiformis, Brachionus plicatilis) and non-enriched newly hatched Artemia nauplii along with microalgae (Chlorella marina, Nannochloropsis oculata and Isochrysis galbana) on larval rearing and survival was elucidated. Fishes in the length range of 55 to 70 mm (presumptive male) and 120 to 150 mm (presumptive female) were selected for pair formation experiments along with single host sea anemone Heteractis magnifica. All the 10 pairs started spawning with in four months after they were shifted to the breeding tanks. Eggs were laid in round patches or clutches at intervals of 15 to 20 days with an average of 2.09 ± 0.3 spawnings per month per pair giving an annual number of 1752 -11832 eggs per pair. Upon incubation for six days in complete darkness, 95-98% of the eggs hatched with the peak hatching between 1830 and 1930 hrs. On 20 th day post-hatch (d.p.h.), most of the larvae metamorphosed to juveniles and began to shift from partially pelagic to epibenthic and the juveniles reached marketable size from 60 th d.p.h. onwards.
Resumen: Se recolectaron larvas de pez en el arrecife Enmedio, Mexico, conarrastres de red y trampas luminicas, en ties ripos de habitat: lecho de talaseas, arena y arrecife. Ambos metodos producen cantidades semejantes de ejempla-res, pero las especies difieren. La red recolecta individuos mas comunes en los arrecifes y las trampas solo funciona-ron bien en el lecho de Lalasea. Los cootenidos del tubo digestivo en 153 larvas de dos clases (3.0 y 5mm) mostraron que las larvas pequenas se alimentan principalmente de tintinidos y dinoflagelados, las mas grandes consumieron pre-sas mayores, como crusticeos y huevos de invertebrado. Traditionally, it has been assumed that re-ef fish recruitment is a density dependent pro-cess determined by adult population size and resource limitations (Sale 1978). More recent ideas on factors regulating population size in-clude the concept that reef populations are strongly influenced by pre-recruitment limita-tions (Victor 1986, Richards and Lindeman 1987, Doherty and Williams 1988). Variation in larval survival rates due to starvation can strongly affect year class strength. Finding ap-propriate planktonic prey within a few days of hatching is critical to larval survival. However, little is known about the diets of early (prefle-xion) larval reef fishes, thus studies of their fe-eding ecology would provide insight into survi-val and subsequent recruitment to reefs. A ma-jor limitation to such studies has been the low yield of reef fish larvae in plankton tows (Victor 1986, Leis 1989). Light traps are an at-tractive alternative since many fish larvae are attracted to light, and traps can be easily deplo-yed in shallow reef sites. We conducted a study to examine the diets of tropical fish larvae co-llected by light traps and plankton tows at dif-ferent habitats on a shallow coral reef. Our ob-jective was to collect first feeding preflexion larvae and to identify prey organisms in their guts. This information is needed for our long term goal of culturing coral reef fishes in the laboratory. Collections were made at Enmedio Reef (19°06'N,95°56'W) located 7 km from the mainland fishing village of Anton Lizardo just south of Veracruz, Mexico (see Tunnel 1988 for details). Enmedio is an emergent platform-type reef (2.25 x 1.15 km) surrounding a 1-3 m deep lagoon that contains both sandy bot-tom and seagrass beds of Thalassia testudi-num. Fish collections were made over three ha-bitats (seagrass, sand and reef with depths of 1-1.5, 2-2.5 and 1.5-2 m respectively) from 12-20 June, 1991. All were evening, surface collec-tions. Light traps (Fig. 1) constructed from 5 gallon plastic buckets had narrow (3 mm) slits to limit entrance of large organisms. These traps floated approximately 2 cm below the surface during the 10 or 15 min sampling pe-riods. Net tows to collect both zooplankton and ichthyoplankton were made using a 0.5 m dia-meter x 1.5 m long 30 \im or 153 JJJTI nitex net pulled behind a boat From 5-10 m^ of water were sampled during tows.
There is a vast literature on distribution, rearing conditions and behavioural studies of clownfishes. However, descriptive information on reproductive behaviour, early developments and life history pathways of Amphiprion ocellaris are scarce. In this study, 7 pairs of A. ocellaris having size 89 to 100 mm (presumptive females) and 40 to 60 mm (presumptive males) were developed through pair formation to generate information on breeding and spawning behaviour, egg morphology, and embryonic, larval, juvenile and adult developments. The spawning was found to be year-round with reproductive cycle of 12 to 15 days intervals and laid 300 to 1000 capsule shaped and adhesive type eggs. The eggs were 1.5-3.0 mm in length and 0.8-1.84 mm in width containing multiple oil globules of varying size and were pale yellow or white for initial two days, turned to black on 3rd to 5th day and silvery on 6th to 7th day of incubation. Hatching took place 168 h after fertilization at a water temperature of 28.5 ± 0.5°C. The ontogeny which began with activation of ovum was classified into embryonic, larval, juvenile, sub-adult, adult and senescent period. The embryonic developments were divided into 29 stages based on the morphological characteristics. The present study is the first scientific report in India on the life history pathways of A. ocellaris commencing from the time of embryonic development to senescent.
The evolution of the digestive enzyme equipment in seabream from hatching to 30 days old larvae was studied; there was a progressive increase in the activity of protease, amylase and acid and alkaline phosphatase from day 15 onwards. The use of specific inhibitors, and SDS-PAGE provided evidence to suggest that most of the proteases belonged to the serine group. A high α-amylase activity was also denoted. Zymograms of larval extracts indicated that exogenous food has more a qualitative than a quantitative role in the secretion of digestive enzymes in this species.
We observed the feeding and swimming behavior of freely swimming cod (Gadus nzorhua) and herring (Clupea harengus) larvae in calm and turbulent (e = -7.4 x 10 -8 m2 s3) laboratory environments at limiting and satiating abundances of Acartia tonsa prey. Attack position rates (a measure of prey encounter rate in unsatiated larvae) were significantly higher in turbulent than in calm water at low food abundances for two size groups of cod. The difference in cod attack position rate between calm and turbulent water was much less when prey was more abundant. Attack position rates of herring larvae were higher in turbulent water than in calm water, but the difference was not significant. Interspecific differences in swimming and pausing behavior were related to differences in prey search strategy used by the two species (cod: pause-travel; herring: cruise). We used a newly developed search model for pause-travel predators in calm and turbulent environ- ments to compare encounter rates for predators using cruise and pause-travel search strategies. Encounter rates for cod and herring larvae, estimated with respective search models, were similar in calm and low turbulence water; at high turbulence levels, the pause-travel model predicts higher encounter rates than does the cruise model. In terms of prey encounter rate, cod larvae benefit more from turbulent motion than do herring larvae. However, aspects of larval behavior other than prey search strategy (e.g. prey capture success) need to be examined experimentally before the overall effects of turbulence on larval fish feeding rates can be fully evaluated.
Recent studies have revealed that reef fish larvae have excellent sustained swimming capabilities and considerable potential for modifying their dispersal patterns by active swimming. However, these studies concentrate solely on the late pelagic phase. We examined the development of swimming abilities from hatching through to settlement in 3 reef fish species (Pomacentrus amboinensis, Sphaeramia nematoptera, Amphiprion melanopus). Larval rearing provided larvae at all stages of development. Experiments were conducted in flow chambers designed for measuring the critical and sustained swimming capability of young larvae. In all 3 species, critical swimming ability increased steadily with age, size, relative propulsive area and developmental stage of the larvae. In contrast, sustained swimming ability showed a marked inflection during development. Differences among species throughout development appear to reflect variations in the developmental patterns of the 3 species. Propulsive area was highly correlated with swimming ability and may prove useful for estimating swimming capabilities among species. The results suggest that some species have the potential to actively modify their dispersal patterns from an early age.
Red drum Sciaenops ocellatus and spotted seatrout Cynoscion nebulosus larvae were collected using plankton and benthic-sled lows every 2 h for 26 h on 4 separate dates in late August to early October 1990 in Aransas Bay, Texas, USA. Gut contents and gut fullness were evaluated to determine if feeding was randomly distributed over depth and time, and to compare feeding between the 2 species. Calanoid copepods were the dominant prey over all size- classes of red drum larvae. Copepod nauplii, bivalve and barnacle larvae were important for small red drum, while calanoid copepods, dinoflagellates and soft-bodied organisms were important in the diets of large red drum larvae. Calanoid copepods and bivalve larvae were the most important food items for spotted seatrout; gastropod veligers and copepod nauplii were also important prey. Gape size was positively correlated with standard length in both species. Mean prey size increased with gape width but there was wide variation in prey size at any given gape width. Small (<3.0 mm) and medium (3.0 to 4.5 mm) fish of both species fed on similar prey but large (>4.5 mm) fish had distinct diets. Similar numbers of larvae were collected in surface and bottom waters (6 m) during the night, but during the day more larvae were collected in bottom waters. Larvae of both species fed primarily during daylight hours. Feeding extended 2 h later in the evening for spotted seatrout than for red drum. There was no significant relationship between current speed and gut fullness in spotted seatrout or in red drum. Larvae were very successful at feeding under all conditions with little indication that vertical distribution was associated with feeding success. Transit periods through well-mixed tidal inlets may provide excellent feeding opportunities, as well as a route to transport larvae to essential nursery habitats.
Breeding and rearing some of the species most commonly used in the aquarium trade actually represent an economical and ecological tool for broadening development, thus the present study investigates captive breeding and rearing of the Sunrise Dottyback, Pseudochromis flavivertex. Egg clutches were obtained from couples maintained in 200 L tanks under controlled conditions. Eggs were laid in PVC pipes and the male normally guarded the clutch until the fry hatched.Hatching took place 96 h post fertilization at 27 °C. Larvae were divided into different experimental groups and fed on different feeding combinations in order to test the importance of food enrichment on larval survival, growth and metamorphosis timing. A first group (Group A) was fed on enriched Brachionus plicatilis and enriched Artemia nauplii; a second one (Group B) on enriched B. plicatilis and not enriched Artemia nauplii and a third one fed on not enriched live preys (Group C) used as control group. Live prey enrichment was essential for rearing this species. In fact, larvae fed on not enriched live preys did not past day 7. Highest survival rates (39% juveniles) were observed in Group A with respect to Group B (11% juveniles). Moreover, evidences of the importance of enrichment on growth and metamorphosis timing were observed since larvae reared using enriched live preys grew faster and completed metamorphosis earlier than those fed on not enriched Artemia nauplii. The results presented here provide additional evidence of the importance of live prey enrichment in ornamental larval fish rearing.
Feeding mechanisms were studied in larval cod from first feeding to metamorphosis. Structural and functional changes that govern jaw movement and control the flow of water through the mouth change in concert with requirements for food energy. Early in development, exogenous food resources supplement the endogenous yolk-sac, viscerocranial structures and functions are simple and nonintegrated, and respiration is cutaneous. Hyoid coupling, which governs mandibular depression via the mandibulohyoid ligament, serves as the major musculoskeletal linkage for opening the mouth. With growth and differentiation of new structures such as the opercular bones, gills, and secondary lamellae, a second musculoskeletal linkage, the levator-operculi coupling, develops. This coupling mediates mandibular depression via the opercular apparatus and interoperculomandibular ligament and supplements hyoid coupling. Changes in musculoskeletal elements become more complex, facilitating obligatory exogenous feeding and branchial respiration. Thus, increases in structural and functional complexity result in the replacement of the simple, less efficient feeding mechanism by a complex combination of feeding mechanisms similar to those found in adult Atlantic cod. © 1996 Wiley-Liss, Inc.
The swimming behaviour and search patterns of pink clownfish larvae, Amphiprion perideraion, were examined using a novel filming apparatus that permits three-dimensional tracking of free swimming zooplankters. Analysis of the resulting search paths included swimming speed and average turning angle, as well as a new approach to the study of search dynamics, fractal analysis. Amphiprion perideraion larvae display a clear shift in behaviour at the onset of feeding, with a drop in overall complexity of their swimming paths and an increase in their swimming speed. Similar to other foraging animals, clownfish larvae display at least two search modes after the onset of feeding: a highly linear ranging mode used to locate patches of food and a highly complex, convoluted searching mode used to exploit those patches once they are located. Conventional analysis did not adequately discriminate between foraging modes, creating the need for fractal analysis. Unlike other foraging animals, clownfish larvae increase swimming speed when they encounter patches of high food abundance. This response is proposed to be the result of hydrodynamic constraints imposed upon the fish because of their relatively small size.
This work addresses the most relevant advances in the breeding and rearing of marine ornamental species. The main breakthroughs in marine ornamental fish culture are discussed, with seahorses deserving a section of their own as a result of their conservation status and unique biology. Details on spawning, embryo development, larval rearing, plankton culturing, and tank design are presented. In addition, with the increase in popularity of ornamental invertebrates in reef aquariums, details on the culturing techniques of some of the most traded invertebrate groups (e.g., live rocks, corals, anemones, polychaetes, mollusks, decapod crustaceans and echinoderms) are also discussed. Finally, the last part of this work highlights the concerns toward the establishment of sustainable collection, production, and trading practices for marine ornamentals as well as the urgent need to develop reliable traceability protocols to distinguish sustainably caught and/or cultured specimens from wild ones. This work represents not only an exhaustive and updated bibliographical source but also a starting point for all those who want to contribute to the development of this fascinating research field.
A major bottleneck in the larviculture of marine fishes occurs immediately following yolk absorption when mass mortality is experienced while transitioning to exogenous prey resources. This study uses a novel approach, digital high-speed videography, to investigate the swimming velocity of zooplankton prey and link predator-induced change in prey swimming speed to the ability of fish larvae to capture prey. We test the hypotheses that (a) size of prey consumed by marine fish larvae is constrained by predator gape and (b) variation in swimming velocity among zooplankton prey is associated with their differential vulnerability to predation by marine fish larvae. Sciaenops ocellatus were cultured from eggs in the laboratory and used to investigate the development of fish-feeding mechanisms and feeding performance. Five zooplankton prey species, including two copepod species, were concurrently cultured and used to examine interspecific differences in swimming velocity with and without the presence of a larval-fish predator. First-feeding larvae use a simple mechanism involving the hyoid-mandible linkage (i.e., hyoid stage) to capture prey. Larvae around metamorphosis capture prey using a more complex mechanism involving the hyoid- and opercular series-mandible linkages (i.e., hyoid-opercular stage). This two-stage development of the feeding mechanism is associated with stage-specific differences observed in feeding performance: less than 50% of larvae fed during the hyoid stage while almost 100% of larvae fed at the hyoid-opercular stage. First-feeding larvae preferred small and less elusive prey; conspecifics at metamorphosis preferred larger and more elusive prey. The two copepod species had the highest swimming velocity among all zooplankton examined, especially with the presence of a larval-fish predator. Prey-capture performance in marine fish larvae is likely affected by the escape response of zooplankton prey. Thus, the authors propose that in addition to size, the swimming velocity and escape response of zooplankton be considered in the selection of an appropriate live feed for marine fish larviculture.
Cranial development in larval Atlantic cod Gadus morhua was studied throughout ontogeny using specimens treated by staining and clearing, scanning electron microscopy and histology. Newly hatched cod larvae have closed mouths, no operculii, five well-developed branchial arches, and transversii ventralis muscles. During the endogenous feeding (yolk-sac) stage, viscerocranial structures remain simple and nonarticulated. Six days after hatching at 5°C, articulation occurs between the quadrate/Meckel's cartilage and the hyomandibula/cranium. Integration of skeletal elements results in a functional jaw that facilitates the transition from endogenous to exogenous feeding. During later ontogenetic stages, the opercular apparatus and levator-operculi coupling develops, facilitating the transition of cutaneous to branchial respiration. Overall, feeding and respiratory needs are met by changes in form (including composition) and function during larval fish growth and are correlated with demands of energy acquisition essential to survival. © 1996 Wiley-Liss, Inc.
The aim of this study was to evaluate the potential use of the harpacticoid copepod Tisbe spp as prey in Amphiprion clarkii larviculture. After hatching, A. clarkii larvae were divided in four experimental groups for feeding studies as follows: group A (control group) fed rotifers (Brachionus plicatilis) followed by Artemia nauplii; group B fed a mixed diet of rotifers and Tisbe spp nauplii followed by a combination of A. nauplii and Tisbe spp copepodites/copepods; group C fed copepod nauplii solely followed by Tisbe spp copepodites and copepods; group D fed rotifers followed by Tisbe spp copepodites and copepods. In this study we observed a positive effect of feeding Tisbe spp copepods in A. clarkii larviculture as a supplement live food to the traditional diet based on rotifers and A. nauplii. In group B larvae, fed a combination of rotifers/Tisbe spp nauplii followed by a combination of A. nauplii/Tisbe spp copepodites-adults, a significant increase of IGF II and IGF I gene expression and a significant decrease of myostatin gene expression was evidenced by Real Time PCR compared to the other experimental groups. In this same group we also observed the best results in terms of growth (total length and weight) and survival.In conclusion, the harpacticoid copepod Tisbe spp may be considered a suitable live prey for marine fish larvae larviculture when used as a supplement to the traditional diet based on rotifers and A. nauplii.
The feeding mechanism of Epibulus insidiator is unique among fishes, exhibiting the highest degree of jaw protrusion ever described (65% of head length). The functional morphology of the jaw mechanism in Epibulus is analyzed as a case study in the evolution of novel functional systems. The feeding mechanism appears to be driven by unspecialized muscle activity patterns and input forces, that combine with drastically changed bone and ligament morphology to produce extreme jaw protrusion. The primary derived osteological features are the form of the quadrate, interopercle, and elongate premaxilla and lower jaw. Epibulus has a unique vomero-interopercular ligament and enlarged interoperculo-mandibular and premaxilla-maxilla ligaments. The structures of the opercle, maxilla, and much of the neurocranium retain a primitive labrid condition. Many cranial muscles in Epibulus also retain a primitive structural condition, including the levator operculi, expaxialis, sternohyoideus, and adductor mandibulae. The generalized perciform suction feeding pattern of simultaneous peak cranial elevation, gape, and jaw protrusion followed by hyoid depression is retained in Epibulus. Electromyography and high-speed cinematography indicate that patterns of muscle activity during feeding and the kinematic movements of opercular rotation and cranial elevation produce a primitive pattern of force and motion input. Extreme jaw protrusion is produced from this primitive input pattern by several derived kinematic patterns of modified bones and ligaments. The interopercle, quadrate, and maxilla rotate through angles of about 100 degrees, pushing the lower jaw into a protruded position. Analysis of primitive and derived characters at multiple levels of structural and functional organization allows conclusions about the level of design at which change has occurred to produce functional novelties.
The relative roles of intrinsic and extrinsic determinants of form in teleost skulls is assessed on the basis of a functional approach to development. The patterns of emerging kinematic connections, changing proportions of structural elements, and their probable functions have been analyzed in phylogenetically closely related lineages with strikingly different modes of development: (1) the oviparous Pomacentridae with free-living larvae subjected to intense environmental selection pressures; (2) the viviparous Embiotocidae which give birth to highly developed juveniles that have been shielded from environmental influences. The developmental patterns in the two groups are very similar. Thus it is suggested that transformations in functional components, changes accompanying the proportional reduction in eye size, and the changes in the functional “hot spots” are governed by internal rules inherited from a common ancestor. It is concluded that internal programmatic rules governing the emergence of morphological variations and transformations and their vitally adaptive functions are inseparably interconnected at the level of the generative process.
The osteological development of Seriola dumerili was studied in a series of 15 cleared-and-stained specimens (6.6-32 mm). The dorsal spine began to ossify by 12.7 mm, and its soft rays by 27.2 mm, and all elements (VII-I, 32) were completed by 23.5 mm. Ossification of dorsal pterygiophores occurred initially by 15.9 mm. Anal fin ray formation (II-I, 20) was completed by 12.7 mm, and soft rays began to ossify at 24.5 mm. Ossification of the anal pterygiophores occurred initially by 15.9 mm. The cartilaginous caudal complex appeared by 6.6 mm NL, and its ossification was completed by 27.2 mm. The fusing of the 1st and 2nd, and the 3rd and 4th hypurals occurred by 8.1 mm. The pectoral girdle contained 5 dermal bones which ossified by 6.6 mm NL, and 3 cartilage replacement bones which ossified by 27.2 mm. The hyoid arch contained 2 dermal bones, six cartilage replacement bones, and 7 branchiostegals (dermal bone) which began to ossify by 15.9 mm. Ossification of the neural and haemal spines was completed by 23.5 mm. Notochord flexion occurred and formed an individual centrum by 6.6 mm NL, and all 24 centra had completely ossified by 12.7 mm. It was previously believed that the hypural complex fusing at a small size at 16.8 mm was an advanced condition. There were 2 plesiomorphic characters, i.e., three predorsals of the back and 3 epurals of the caudal complex, found in S. dumerili. In addition, there were also 2 apomorphic characters, i.e., a stay on the proximal radial and a double fin-ray on the last distal radial of the 2nd dorsal and anal fins, found in S. dumerili. http://www.sinica.edu.tw/zool/zoolstud/40.4/289.pdf.
Summary We examined the hypothesis that fish species with similar ecomorphological patterns, but from different taxonomic groups, would use similar feeding modes. We contrasted the feeding behavior of Micropterus salmoides (Lacépède) (Centrarchidae) and Cichla ocellaris (Block and Schneider) (Cichlidae), both large-mouthed piscivores with a locomotor morphology designed for fast acceleration, with Lepomis spp. (Centrarchidae) and Cichlosomaseverum (Heckel) (Cichlidae), both small-mouthed predators on benthic invertebrates with a locomotor morphology designed for maneuverability. Pressure profiles in the buccal and opercular cavities were more similar for species that shared ecomorphological patterns than for species that shared phylogenetic histories. For small- mouthed predators, minimum buccal pressures were significantly greater and occurred earlier than the corresponding opercular pressures. For both large-mouthed predators, minimum buccal and opercular pressures were similar in magnitude and in timing. We developed the ram-suction index (RSI) to identify the relative contributions of ram feeding (i.e. predator movement) and of suction feeding (i.e. prey movement) to shortening the predator-prey distance during the strike. The RSI values for small- mouthed predators fell closer to the suction end of the ram-suction continuum than did strikes by the large-mouthed predators. The RSI provides a bench mark for evaluating the hydrodynamic consequences of intraspecific , interspecific and interprey variation in strike mechanics.
The reproductive behavior, embryonic development and early larvae of Priolepis nocturna are described. Three pairs of P. nocturna began spawning 41 days after acquisition and maintained a 5–10 day spawning cycle lasting beyond several months. Spawning was initiated by the female who signaled her readiness to spawn by displaying to the male. Egg clutch size averaged 1578±51.23 eggs and ranged from 268 to 3121. Egg length averaged 0.82±0.01 mm total length (TL) and ranged from 0.75 to 0.90 mm. Egg width averaged 0.51±0.51mm total width (TW) and ranged from 0.49 to 0.52 mm. Fertilized eggs were ovoid in shape and attached to the ceiling of provided shelters via adhesive filaments at the proximal end. Hatching rates averaged 97.3±0.51% and ranged from 91.9 to 99.8%. Larvae measuring 1.89±0.04 mm TL hatched 121±0.5 h post fertilization and did not rotate position prior to hatching. Skeletal elements of the chondrocranium were simplistic and dominated by the hyoid, hyomandibulosymplectic cartilage, ethmoid and Meckel's cartilage in first feeding larvae. No elements were added to the cranial architecture by 5 days post hatch (DPH) when larvae measured 2.05±0.04 mm TL. First feeding larvae consumed only dinoflagellates and tintinnids suggesting that feeding was constrained by a poorly developed feeding mechanism. Embryology and larval development are described to 5 DPH.
The swimming and feeding behavior of laboratory-reared larval anchovy, Engraulis qnordax, was described over the first 30 days of larval life. Estimates were made of cruising speed, proportion of time spent in rest, and burst speeds. Tail beat frequency, tail heat amplitude, and speed of swimming larvae were measured from cine photographs and the relationship between these variables determined. Complete and incomplete feeding sequences were described in detail from cine photographs and the frequency of feeding acts determined from visual observation. The extent of the reactive perceptive field for prey was measured from cine photographs and expressed as a function of larval length. Feeding success of larvae fed rotifers was determined for the first 21 days of larval life. These estimates were combined to estimate the volume of water searched by larvae per hour, and this estimate and others were used to calculate the density of food required by larvae to meet metabolic requirements. These calculations indicated that the densitv of food required by larvae just after yolk absorption was up to 37 times that required by older larvae. In this report I describe the feeding and swim- ming behavior of the larval anchovy, Engradis mordux, during the first 30 days of larval life. These observations will be combined with results of other studies in a model for estimation of the survival of larval anchovy in the sea. Similar studies of feeding and locomotor behavior have been made on other larval fishes (Blaxter, 1966; Braum, 1967 ; Rosenthal and Hempel, 1970), and the biology of larval fishes in general has been reviewed by Blaxter (1969).
Feeding strikes of Atlantic salmon (Salmo salar) alevins preying upon Daphnia are described using videorecording of synchronous lateral and antero-ventral views. Based on examination of characteristics such as aiming inaccuracy and capture distance, it is demonstrated that feeding behavior significantly improves during the first 2 wk after initiation of exogenous feeding. With increasing experience, young salmon tend to capture prey more quickly and with greater accuracy. First-feeding alevins use a body-ram feeding mode, relying on their swimming motion to overtake and capture prey. After 7–10 d of feeding, the fish change to a suction feeding mode that effectively uses suction generated by expansion of the orobranchial chamber to pull in prey from a distance. Also, feeding behavior of alevins raised on a commercial salmon feed lags developmentally behind the behavior offish raised on live food. This lag time is short (2–3 d), indicating that despite reports to the contrary, hatchery-raised fish do not require a Song time to learn to capture prey effectively in the wild.
The reproductive behavior of Gobiosoma oceanops in aquaria is briefly reported and the embryology of the eggs obtained is described. Twenty stages have been assigned on the basis of gross morphology. Relevance for reorientation of G. oceanops embryos is discussed and a comparison is made with reorientation described for Bathygobius soporator embryos. The pterin compound, sepiapterin, has been identified as the visible larval xanthophore pigment.
Copepods are the natural food items for marine fish larvae but are still difficult to be cultured on a continuous basis. Therefore, suitable storage techniques for copepod subitaneous eggs are of great interest. Cold-stored copepod embryos still develop and retain a physiological activity during the cold storage period. As a consequence, their nutritional quality may change over the time of storage with these changes possibly affecting both eggs viability and larval fish survival and development. In this study, the clownfish, Amphiprion polymnus, was used as an experimental model to compare, for the first time, the effects of diets based on enriched rotifers and Artemia (control), Acartia tonsa copepods of a continuous culture and A. tonsa originated from 6 months cold-stored eggs. The effects of the different diets were tested through morphometric, molecular and biochemical approach. This study demonstrated that after a 6 months cold storage period, the quality of copepods obtained from those eggs was suboptimal for A. polymnus larval rearing. In fact, larvae fed those copepods showed lower growth and survival performances respect to the other experimental groups.
Rotifers and Artemia salina nauplii are the most widely used live prey for newly hatched larvae, but they do not always promote optimal survival and growth. Alternative food sources such as copepods, which bypass these inadequacies and promote adequate growth, are needed and they are viewed with considerable interest by the scientific community. The aim of the present study was to test two different diets [rotifers and A. salina nauplii (group A) and a mixture (group B) of rotifers/Tisbe spp. copepods and A. salina nauplii/copepods] during the larval rearing of the striped blenny Meiacanthus grammistes. The analysis of the survival rate, size (total length and wet weight) and metamorphosis time during the larval phase of this species showed that Tisbe spp. administration can significantly improve larval survival and growth and also reduce the metamorphosis time. The results obtained are related to the fatty acid content of the live prey used and are essential in order to improve the captive production of M. grammistes through a closed system and, in turn, to preserve natural stocks.
Introduction Development, Distribution, and Analysis of the Survey Questionnaire The Hobbyist Response: Those Who Culture for Love The Commercial Response: Those Who Culture for Money The Scientist's Response: Those Who Culture for Knowledge Contrasts and Parallels in Culture Efforts of Hobbyists, Breeders, and Scientists Summary
Ontogenetic change in the visual acuity of Premnas biaculeatus larvae was determined both behaviourally and anatomically. Visual acuity improved substantially between early feeding (day 3 post-hatch) and the pre-settlement (day 10 post-hatch) larvae but, at both ages, the anatomically-measured visual acuity was greater than that determined behaviourally. It appears that estimated anatomical visual acuity values substantially over-estimate the functional visual acuity realized under normal conditions. The distribution of the reactive angles indicated that most frequently prey within 0 to 9° of the longitudinal larval axis elicited a feeding response at both larval ages. This suggests that stereoscopic vision is used extensively during feeding in this species. The prey capture success with rotifers ranged from 96% at 3 days post-hatch to 100% at 10 days post-hatch. These values differ markedly from previous studies on temperate species and highlight the well developed abilities of larval P. biaculeatus at a given
Two groups of largemouth bass, Micropterus salmoides, were reared in the laboratory. One group was reared on an artificial, passive diet (frozen brine shrimp) whereas the second was reared on a natural, active diet (cultured zooplankton). Observations on the development of feeding behaviour indicated that the motor patterns and duration (number of weeks in the behavioural repertoire) of the feeding acts did not differ between fry reared on the two diets. While feeding on their respective diets, natural-diet fry performed significantly more orientations and bites, the two major early feeding acts, than did the artificial-diet fry. When tested with live fish prey, fish reared on the natural diet performed fewer orientations and strikes and captured more prey per fry than did the artificial-diet fry. Natural-diet fry had a significantly better net efficiency (captures minus strikes minus orientations) than did artificial-diet fry. Diet, experience, and length (T.L.) of fry affected their predator efficiency significantly. We argue that providing hatchery-reared bass fry with an opportunity to prey on live forage fish once or twice before their release would enhance their survival and eventual recruitment into natural populations.
At present, clownfishes are the best example of successfully captive bred ornamental specimens but little is known about the relationship between food enrichment and both larval growth and development. In fact, it is well known that a certain percentage of these fishes cultured in captive conditions show a miss-band pigmentation. In the present study, the effects of live prey enrichment on growth and pigmentation in false percula clownfish (Amphiprion ocellaris) larvae were tested.Newly hatched A. ocellaris larvae were divided in three different groups and fed as follows: group A fed on enriched (Algamac 2000) B. plicatilis (10 ind./mL) from day 1 to day 5 post-hatch (ph); group B fed on enriched (Algamac 2000) B. plicatilis (10 ind./mL) followed by Artemia nauplii (5 ind./mL;) and group C fed on Algamac 2000 enriched B. plicatilis and Algamac 2000 enriched Artemia nauplii.Samples of the larvae were collected on day 5 from group A and on day 11 ph in group B and C for morphometric and molecular analysis. On day 11 ph food enrichment resulted in a better growth of group C larvae respect to those of group B fed on not enriched Artemia nauplii (15.8 ± 0.2 mg and 8.78 ± 0.02 mm vs. 6.8 ± 0.2 mg and 6.93 ± 0.01 mm). Moreover, 36 ± 2% of the juveniles obtained from group B showed a miss-band pigmentation as compared to 29 ± 1% of the juveniles obtained from group C. At molecular level, the results obtained by Real-Time PCR are in agreement with the morphometric ones: a positive induction of the Insulin-like Growth Factor II (IGFII) and Peroxisome Proliferator Activated Receptor α and β (PPARα and PPARβ) gene expression and a reduction of Myostatin (MSTN) was observed in group C larvae fed on enriched live prey. IGFI gene expression was higher in group B.The present study provides clear evidences of the positive role of Algamac 2000 on growth and pigmentation of captive cultured false percula clownfish.
The size at which feeding structures developed and shifts in head proportions occurred, differed between Atlantic cod Gadus morhua and winter flounder Pseudopleuronectes americanus. The sequence and timing of the development of feeding structures may not be dependent on size, but may occur because they are necessary to meet specific requirements offish larvae feeding in the plankton. In early larval stages development of feeding structures was similar in number and type and was necessary for first-feeding in both species. In later stages, significant differences between species occurred in the timing of the development of feeding structures. In cod differentiation of new structures and changes in head proportions occurred at about two-thirds of the way through larval life, which coincided with an increase in growth. In flounder changes in feeding morphology did not occur during the symmetrical larval stage, but occurred only after metamorphosis to the asymmetrical demersal juvenile stage. Differences between cod and flounder in the size at which feeding structures develop may reflect life history adaptations expressed in the duration of the pelagic larval stage, as well as differences in juvenile habitat and feeding ecology.