The European catfish, Silurus glanis L., has become an important aqua cultural fish in Croatia, and it is cultivated extensively in ponds in polyculture with carps. The development of the digestive tract in S. glanis was studied with the aim of improving intensive fish production. Research was carried out on S. glanis larval stadium from 1- to 19-day post-hatching (DPH). The main histological methods used were: haematoxylin and eosin staining, periodic acid Schiff staining (PAS), Alcian blue (AB) and toluidin blue staining (TB). A yolk sac was present during the first 5 days (1-5-DPH). During the initial 3-DPH period, there was no trace PAS and AB activity in the digestive tract. Differentiation of the digestive tract began at 3- to 5-DPH. The oesophagus was positive for AB at 5-DPH, PAS and TB after 7-DPH. Differentiation of enterocytes began at 5-DPG and the intestines were complete at 11-DPH. Development of liver and pancreas was also studied. The analysis of data obtained in this study suggests that after 5-DPH catfish larvae have morphologically completed digestive tracts.
"e for a successful transition to exogenous feeding or delaying time of first feeding without affecting larval growth performance ( Gisbert and Williot , 1997 ) . These results contrast to most other freshwater species where this period is either non - exis - tent or lasts just a few days ( Kamler , 1992 ; Ostaszewska , 2005 ; Sysa et al . , 2006 ; Kozaric et al . , 2008 , among others ) ."
[Show abstract][Hide abstract] ABSTRACT: The ontogeny of the digestive tract in Cichlasoma urophthal-mus was studied by means of optical microscopy from hatch-ing to 30 days post-hatching (dph; 855 degree days, dd). The development of the digestive system in this precocial species was a very intense and asynchronous process, which pro-ceeded from both distal ends interiorly. At hatching, the digestive tract consisted of a straight tube with a smooth lumen dorsally attached to the yolk-sac. The digestive acces-sory glands were already differentiated and eosinophilic zymogen granules were visible in the exocrine pancreas. At the onset of exogenous feeding between 5 and 6 dph (142.5–171.0 cumulative thermal units, CTU), the buccophar-ynx, oesophagus, intestine, liver and pancreas were almost completely differentiated, with the exception of the gastric stomach that completed its differentiation between 11 and 14 dph (313.5–399.0 CTU). The development of gastric glands at 14 dph and the differentiation of the stomach in the fundic, cardiac and pyloric regions at 19 dph (541.5 CTU) were the last major events in digestive tract development and designated the onset of the juvenile period. Remnants of yolk were still detected until 16 dph (456.0 CTU), indicating a long period of mixed nutrition that lasted between 10 and 11 days (285.0–313.5 CTU). The results of the organogenesis of larvae complement previous data on the functionality of the digestive system and represent a useful tool for establish-ing the functional systemic capabilities and physiological requirements of larvae to ensure optimal welfare and growth under aquaculture conditions, which might be useful for improving current larval rearing practices for this cichlid species.
"The ontogenetic development of the digestive enzymes has been described in many marine and freshwater fish species (Chakrabarti et al., 2006; Kumar et al., 2000; Lazo et al., 2011; Zambonino-Infante et al., 2009 among others). Among them, several studies have evaluated the morpho-anatomical development of the digestive tract and accessory glands in several catfish species (de Amorim et al., 2009; Kozarić et al., 2008; Liu et al., 2010; Pradhan et al., 2012; Segner et al., 1993; Verreth et al., 1992; Yang et al., 2010). However, little is known about ontogenetic and dietary-induced changes in digestive enzyme production in different catfish species during early life stages of development outside of a few exceptions on sheatfish Silurus soldatovi (Liu et al., 2010) and striped catfish Pangasianodon hypophthalmus (Rangasin et al., 2012). "
[Show abstract][Hide abstract] ABSTRACT: The digestive physiology of butter catfish was studied by assessing the activity of different pancreatic (trypsin, chymotrypsin, alpha-amylase and lipase), gastric (pepsin) and intestinal (alkaline phosphatase) enzymes from hatching until the juvenile stage (30 dph). Larvae were reared at 27 degrees C and fed with Artemia nauplii from 2 days post hatching (dph) until 10 dph, from 7-10 dph with Artemia nauplii and zooplankton (Cyclopoida) and from 10 dph onwards only with zooplankton. The assessment of the activity of digestive enzymes showed that enzymes involved in the digestion of proteins, lipids and carbohydrates were present in butter catfish larvae before mouth opening and increased after the onset of exogenous feeding, coinciding with the histological organization of the exocrine pancreas. The specific activity of most of the pancreatic enzymes increased until 15 dph and decreased thereafter coinciding with the increase of pepsin. A progressive shift in activity from alkaline (trypsin and chymotrypsin) to acid (pepsin) proteases indicated a change in the digestive physiology of the specimen, as alkaline proteases were no longer the main digestive enzymes involved in protein digestion after the onset of acidic digestion between 15 and 21 dph. The maturation of the intestine and the achievement of a juvenile-like mode of digestion were demonstrated by changes in enzyme activities from the exocrine pancreas and stomach that coincided with alterations in enzyme production occurring in the intestine (e. g. alkaline phosphatase). Considering the ontogenetic development of the digestive enzymes from the pancreas, stomach and intestine, butter catfish larvae might be weaned between 15 and 21 dph, as larvae have achieved the complete maturation of their digestive capacities. These results contradict previous recommendations, which were based solely on the histological organization of the gastric gland and histochemical properties of mucous cells from the stomach, to wean butter catfish larvae at earlier ages. These findings on the functional development of the digestive system in butter catfish would be useful to improve the actual larval rearing techniques for this promising catfish species from the Indian sub-continent.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.