Fish Nutrition - Science topic

As per I know, Acrylic (PMMA) and thermoplastic polymer (PC-7) materials would be a good choice and economically beneficial solution to build a UV permeable enclosure system specially for a shallow waterbody. oh, they are long lasting, recyclable and easy to operate.

Nagajothi Velayuthapillai - According to https://quillbot.com/ai-content-detector, 100% of your answer is actually generated by AI.

If you use AI always check the references. Mostly, they too are made up. That's classic AI behaviour. The last reference by Hart and Reynolds is real (2002) but deals with wild capture stock assessment, which is irrelevant to the discussion.

I agree with the two answers, thanks for your help.

Hey there Chouaib Siouda! Making fish food float is a piece of cake. All you Chouaib Siouda need is a bit of kitchen ingenuity. Try mixing gelatin with your usual fish food concoction. The gelatin will give it that buoyant kick. It's like the jelly of the fish world – they'll be swimming up for more in no time. Experiment with the ratios until you Chouaib Siouda achieve the perfect floating feast for your aquatic buddies. And remember, it's all about keeping those fish fins flapping!

In general, they can eat both, but floating food is preferable because it allows better assessment of the amount they are consuming, helping to avoid contamination or overfeeding.

We have almost identical cases. I'm also in fish nutrition, and in our recent tilapia trial, we have observed such lesions and behavioral signs.

In our case, I believe the root cause was aggressive interactions, but secondary bacterial infection might have taken over after. It is difficult to ID the pathogen, however, without proper microbiological analysis. Following this.

please write to me at nagajothi@tnfu.ac.in

I am interest,

But is it possible to do contribute from the prt of my dissertation?

Thank you

Both probiotics and prebiotics have promising roles in fish nutrition, but their specific applications and benefits may vary depending on the species of fish, the rearing conditions, and the desired outcomes. Here's an overview of both probiotics and prebiotics in fish nutrition:

1. Probiotics: Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. In fish nutrition, probiotics can have several positive effects:

- Improved gut health: Probiotics can promote a healthy gut microbiota by inhibiting the growth of harmful bacteria and pathogens, enhancing the integrity of the intestinal barrier, and modulating immune responses.

- Enhanced nutrient utilization: Certain probiotic strains can help improve the digestion and absorption of nutrients, including proteins, lipids, and carbohydrates, leading to enhanced growth and feed conversion efficiency.

- Disease prevention: Probiotics can have immunomodulatory effects, stimulating the fish's immune system and providing protection against pathogens. They can help prevent or reduce the severity of diseases in fish.

- Water quality management: Probiotics can contribute to maintaining a balanced microbial community in the aquatic environment, reducing the accumulation of harmful bacteria and improving water quality.

However, the effectiveness of probiotics can vary depending on the specific strain used, the fish species, and the rearing conditions. It's important to select probiotic strains that are well-adapted to the host species and have demonstrated positive effects in scientific studies.

2. Prebiotics: Prebiotics are non-digestible compounds that selectively stimulate the growth and activity of beneficial bacteria in the gut. They serve as a substrate for beneficial microorganisms, promoting their proliferation and activity. In fish nutrition, prebiotics offer several potential benefits:

- Enhanced gut health: Prebiotics can stimulate the growth of beneficial bacteria, such as lactic acid bacteria and bifidobacteria, in the fish gut. This can contribute to a more stable and diverse gut microbiota, supporting optimal gut health and function.

- Improved nutrient absorption: By promoting the growth of beneficial bacteria, prebiotics can enhance the fermentation of dietary fibers and improve the utilization of nutrients, including short-chain fatty acids, vitamins, and minerals.

- Immune modulation: Prebiotics can have immunomodulatory effects, influencing the fish's immune system and promoting a balanced immune response. This can help improve disease resistance and overall health.

- Stress mitigation: Prebiotics may have stress-mitigating effects by improving the gut-brain axis communication and reducing the negative impacts of stressors on fish.

The effectiveness of prebiotics can depend on factors such as the type and dosage of prebiotic used, the fish species, and the diet composition. Identifying suitable prebiotics and determining their optimal inclusion levels are important considerations for achieving desired outcomes.

In conclusion, both probiotics and prebiotics have promising applications in fish nutrition. Probiotics can directly introduce beneficial microorganisms to the gut, while prebiotics promote the growth of existing beneficial bacteria. Depending on the specific requirements and goals, a combination of probiotics and prebiotics (synbiotics) may also be considered to achieve synergistic effects. It is essential to conduct thorough research and consider the specific conditions and requirements of the fish species in question to determine the most effective approach.

Krishna Pada Singha sir In majority cases sucrose is used in tissue homogenate preparation as it acts as a cushion, and give you better separation of cell fractionation, less contamination between these fraction , also it maintains osmotic strength of the buffer while having low ionic strength. Furthermore, for low ionic strength, sucrose is fine in case of higher ionic strength Mannitol is recommended. Mannitol elevates blood plasma osmolality, resulting in enhanced flow of water from tissues

Dear Mohammed,

The problem of precipitating large aggregates biofloc particles still one of the most problems that obstacle the sustainability of that technology. solving this need more creative thinking.

Apart from the examples already given, a few more are leaves of Ocimum tenuiflorum and Prosopis juliflora.

There are three most possible routs for vitamine take up by fish during immersion:

1. Through the soft tissues lining mouth cavity

2. Via gill lamillae during respiration process where large volume of blood became in direct contact with flowing water.

3. Through the limited quantities of water which ingested into the digestive system by drinking.

Dear Judine:

As the others have mentioned, your choice of the control feed has some options. In general, I'd agree with Mr. Esmaeili that the diet needs to be more of an optimum, since your experimental diets will be comparing growth, survival, etc. from this "baseline" diet.

In the second question, you ask if you can use a feed prepared by a commercial supplier. This may be more difficult. Most commercial mills manufacture diets based on a "least cost" formulation which involves the substitution of ingredients based on cost and availability. In that case, the formulation may change from batch to batch. This, then, would not be a suitable product to use as your control...because you might end up using different feeds for your experiments.

If the mill will provide you the formula, that may be helpful. Even then, you would be best to be at the mill during manufacturing to verify the ingredients are being used as expected. My suggestion is to confirm the best common formula for your area, including ingredients, and be at the mill to verify the feed being produced meets your expectations. In this way, you can be certain your control feed is as you expect.

Hello, What do you think about freeze the jellyfish in plastic bags ?

Dear Hussain

There are so many software available to make a formula but they may be an expansive. By using Microsoft Excel itself we could make a formula for any fed animals. There are wide range of ingredients with various nutrient composition and price. Giving a preference to the cheapest and friendly available ingredients is always desirable and at the same time the selected ingredient has to be accepted by the cultured species without having any negative impact.

Prior to formulation ensure the following

1. Nutrient composition ingredients used for a formulation

2. Nutrient requirement of cultured species

Notwithstanding, having a knowledge on the range of inclusion level of each ingredients is vital. Since, the inclusion level of ingredients is not same and would be differ animal to animal.

Dear Ototo,

In dietary vitamin supplementation, care must be taken to take account of vitamin losses during diet processing or storage conditions. Indeed, vitamins are prone to be lost because of exposure to adverse environmental conditions such as high moisture, temperature or light, and water-soluble vitamins may also be lost through leaching in water. In contrast to watersoluble vitamins, that are excreted when fed in excess, fish accumulate fat-soluble vitamins when dietary intake exceeds metabolic demand. Under such conditions, hypervitaminosis may be observed although it is unlikely to occur under practical feeding conditions.

Fish may obtain minerals both from the diet and the surrounding water, and it is difficult to provide mineral-free water for mineral requirements studies. Moreover, dietary mineral supplementation is quite inexpensive, and therefore, it is easy to avoid mineral deficiency problems in aquaculture As a portion of mineral requirements of fish may be met by the surrounding water, and most minerals are also present in adequate amounts in dietary ingredients, the list of minerals that are likely to be deficient in aquafeeds is relatively short: P, Zn, I, Cu and Se. Fish regulate the body concentration of several minerals by absorbing or excreting them from the water; however, some minerals such as Pb, Cd, Cu or Hg are poorly regulated and may accumulate in the body, eventually becoming toxic. Therefore, attention must be paid to levels of these minerals in the diets and within body stores to avoid health problems.

Availability and utilization of minerals by fish is dependent on dietary source and level, concentration in the surrounding water, body stores and interactions with other minerals or other nutrients. Several mineral/mineral and mineral/vitamin antagonistic or synergistic interactions wiil be happen and must be taken into consideration when defining dietary nutrient levels. For instance, Ca, P and phytate are well-known inhibitors of Zn availability. Therefore, diets including high levels of fish meal (rich source of Ca and P) or phytate require higher Zn levels.

This reference has been published on the composition of the eggs of three species in captivity (including copper) . Regards

Devauchelle, N., Brichon, G., Lamour, F., & Stephan, G. (1982, January). Biochemical composition of ovules and fecund eggs of sea-bass (Dicentrarchus labrax), sole,(Solea vulgaris) and turbot (Scophthalmus). In International Symposium on Reproductive Physiology of Fish Wageningen, the Netherlands 2-6 August 1982. (online)

To answer your second question Jessica, I'm not sure if there would be specific phospholipid classes enriched above others. Is there a high protein content in the diet? The high nitrogen content of the proteins could enhance the phospholipids for sure, the head groups of PS, PE, PC and the sphingolipids (if this organism has these) can all come from serine. What is the specific aqua organism you are dealing with? Ultimately I would hypothesise that the diet is too rich so that there is no need for the organism to have many neutral lipids and a variety of the other lipids is being made instead.

It depends on you balanced n-3/n-6 or EFAs or not, If these fatty acids are balanced and there are some left of dietary lipid that you want to fulfill to reach the lipid level aimed. Any source of lipid can be used. In the same way, if you want to replace marine oil by plant oil, maximum replacement level should not impact balance of n-3/n-6 ratio or EFAs. Importantly, please check that how you fish or shrimp that you aimed to study utilize lipid well or not, if bad please control lipid level in diet in which provided optimum EFAs and the rest may be a little bit increase of protein or carbohydrate 

I very much appreciate the answer given by the previous scientist.  The substrate is not a pure material It is a mixture of components.  To break down the various components studded therein, the exogenously supplied multi  enzyme  complex will always work better than a single enzyme.

Histopathology is primarily about pattern recognition.  You are looking for changes in structure and colour that indicate a deviation from the norm. So I generally scan the slde first with a x20 objective so that I can quickly locate any significant lesions, then I scan the areas of interest with a x40 objective (the best that I can afford) and I take time - 5 minutes average per slide.  I use the x100 oil only for resolving fine detail that the x40 will not show clearly.

Associated with this is the need to know what is "normal" because tissues change with the physiology of the animal, build up a reference set of "normal".  I also I spent some time with the histologist learning what artifacts look like (She made me sets of slides with deliberate errors - understaining, overheating etc. Great fun!).

Finally, it is really important to participate in a regular "show and tell" session with fellow pathologists and shre your findings. That way you learn off each other.

Remember that the pictures you see in books and papers are not the average - they are extreme examples used to prove a point. Reality is never so obvious.

Thank you Imtiaz Ahmed Sir, for adding answer to my query. Sir,  can you please share some base line data if it is available with you.

Any animals do you mean?

Differ from one type to another, but generally; These fatty acids are important for maintaining your Pets joint health. Look for Pets foods that contain fish oil or fish products, as well as flax seed or canola oil, which all contain high levels of omega-3 fatty acids. You can also purchase supplements that contain omega-3 fatty acids.

Unlike farm animals; Diet Composition Drives Animal Health, Growth Rates, Production Costs & Financial Returns

As many who work have worked with fats and oils are undoubtedly aware, an important feature of fats and oils, known collectively as

lipids1

, is their versatility. Fats and oils serve a number of important nutritional and non-nutritional functions. They have multiple benefits

from optimizing pelleting products, machinery life, feed throughput and formula density; to controlling dust in feed mills and in barns; to

the ability to affect nutrient and energy levels, energy density, feed efficiencies and thermo-body regulation; to impacting animal growth

rates by influencing average daily growth (ADG) rates, particularly in younger pigs.

Before we get into the specifics of fat/oils as an energy source, it is often helpful to understand the primary components of feed rations,

as well as the principal drivers of feed costs which normally account for 60-70% of overall costs of production. Why is this important?

Feedstuff selection can often play a major role on operator profitability because most producers, unfortunately, are price takers vs.

price makers, and small savings in feed costs, or a corresponding improvement in feed efficiency or average daily gain, can drop to the

producer’s bottom line, multiplied across each pig in production.

Swine diets must be balanced to contain the necessary nutrients to nourish the animal. Required nutrients include energy, amino acids

(from proteins), minerals and vitamins. Recommended swine diets will vary depending on the nutrient requirements for pigs, which in

turn will vary according to their stage of production and health, gender and genetic line, lean growth rate, whether they are gestating,

producing or consuming milk, and ambient weather and barn conditions.2

When afforded ad libitum (“eat at will”) access to feed, pigs in experimental settings will eat until their energy requirements have been satisfied.

However, in commercial production most pigs do not enough energy to meet their energy needs for maximum protein deposition and growth. This

is one of the reasons why adding fat to the diet in commercial situations can improve growth rates that surpass university study (high intake)

conditions (Mike Tokach, KSU, personal communication, Apr 2012).

In addition, fat can be utilized not only to provide energy but fat-soluble vitamins, essential fatty acids, and even molecular signaling

substances. Often the amino acid which is the most important limiting factor in grain-soybean meal diets is the amino acid lysine (used

in the synthesis of new tissue).3

It is the cereal grains which are used as base feed ingredients because they are low in fiber and high in

energy. However, all grains are deficient in protein quantity and quality, as well as minerals and vitamins, so additional ingredients are

normally required to balance the ration.

Soybean meal is an excellent source of amino acids, which forms the basis for balancing diets vs. looking to soybean meal simply for

its crude protein value. Diet formulation can be a bit tricky when fat is used since its impact is to reduce feed consumption. Lysine

requirements need to be increased so that animals obtain the required amounts to allow maximum growth to take place.4 For more

information on balancing swine diets, please see (van Heugten et al, 2007.)

Dear Ihilesen

Listed below a number of sites that wish can benefit of them

Best regards

Amjed K. Resen

M Lauff, R Hofer - Aquaculture, 1984‏ - Elsevier‏

L Ribeiro, JL Zambonino-Infante, C Cahu, MT Dinis - Aquaculture, 1999‏ - Elsevier‏

G Rosenlund, J Stoss, C Talbot - Aquaculture, 1997‏ - Elsevier‏

J Walford, TJ Lam - Aquaculture, 1993‏ - Elsevier‏

Dear Fahma,

Please check the following resources.

Best regards

SM Najim

Dear Mohammed,

I agree with Dr. Najim, additionally you should also tell us whether you are going to raise larvae/fingerlings (young fish) or older fish (Larvae and Fingerlings need the feed with higher protein content than older fishes). In our fish farms feeds represent up to 70% of production costs. The Fish nutrition manual prepared by us is unfortunately available only in Russian language. For the balanced fish feed formulation you can use following very useful source (see attachment).

Look also following links:

With best wishes

Bakhtiyor

Dear Paraskevi,

Please check the following resources.

Regards

SM Najim

Dear Adel Al- Dubakel

Send your file I hope that you find the answer

BEAST Wishes

Amjed K. Resen

Dear Dr. Adel,

I found information about universal pellet extruder including photos. I hope it will be helpful. Please refer to the links below.

Best regards

SM Najim

Nitrogen Free Extract (NFE)

NFE is determined by mathematical calculation. It is obtained by subtracting the sum of

percentages of all the nutrients already determined from 100.

%NFE = 100-(%moisture + %CF + %CP + %EE + %Ash)

NFE represents soluble carbohydrates and other digestible and easily utilizable non-nitrogenous substances in feed.Total carbohydrate component was crud fiber and soluble carbohydrate (NFE), NFE was the source of energy since most fishes can not digest fiber.

A.Y.Al-Dubakel

Egg quality is complex even in species which we have kept domesticated for several generations. I believe egg quality is mainly influenced by genetics, the health and nutritional status of the broodfish, environmental conditions during fertilization and egg incubation (temperature and water quality in general) and off course the managing of the fertilization, desinfection, sorting etc. So many parameters to control there...I think that also number of eggs pr female (related to weight) is interesting together with fertilization rate and hatching rate. In salmon we also experience that the result of sub optimal egg quality can be more prominent during later stages like after hatching  and startfeeding. So mortality during startfeeding and also mortality from hatching to startfeeding could also be some good indicators. If there is something not optimal with your egg quality, I would also expect a higher rate of deformed fry.

Dear Dr. Adel,

Vitamin C is known as a potent antioxidant, so it will be destroyed very fast in water by several oxidative compounds such as dissolved oxygen, chlorine and similar compounds.

However, confirmation of symptoms is highly recommended because they are widely interfere with other causative agents, you may find some useful ideas in within the attached links.

With best regards.    SM  Najim

http://m.petco.com/shop/en/petcostore/product/atm-paradigm-all-natural-vitamin-c-water-conditioner-for-aquariums 

Probably the spherical lens of the eyes of prey (teleost fish). The protein of the lens is not easily digested. 

This is very common in the stomach of predatory fish.

The answer by David nicely illustrates the most importants points in doing this type of work.

One more remark: in using this approach, you assume that the digestibility of the basal diet does not change regardless of the ingredient  and its amount added to that basal diet. Also you assume that digestion goes on more or less undisturbed.

 This is certainly not always true. We have seen that fat containing ingredients might easily cause problems in the digestive process making the results sometimes hard to interpret.

Hellow Nawras A. Al-Faiz

please check pdfs

Thanks a lot dear Amit.

See:

Hinshaw, Jeffrey M. "Effects of illumination and prey contrast on survival and growth of larval yellow perch Perca flavescens." Transactions of the American Fisheries Society 114.4 (1985): 540-545.

I agree with you. 

Feed comprises the largest production cost for aquaculture industries in which it is extremely high, being up to 70% of the total cost. For this reason, the research for alternatives to fish meal is one of the first international research priorities. Soybean meal and other plant protein induces enteritis in the distal intestine of Atlantic salmon and rainbow trout. When producing organic feed and fish, these substances must be investigated effects on the fish intestine and liver inflammation.

There is a reference in poultry. However, the practice is discouraged because of the chances of contamination from heavy metal and other toxic substance. 

http://nectar.northampton.ac.uk/5238/3/Paul20135238.pdf 

You can use log-linear model to do the contingency table analysis, and using G² =-2log(L) (follow Chi-square distribution and addable)to measure the model fitting and significance. Your data have a lot of zeros, you need make sure, are them random zero or structure 0. If structure zero, no parameter is estimated for that cell. The degree freedom will decreases. Say X=4, if you think there is no specie 4 in any location, , they are structure zero, you can delete x=4. If random zero and you use SAS GENMOD or CATMOD, those zeros will be replaced by a small number. The full model with X, Location and X*Location with perfect fitting. Without interaction, is called main effect model, it assumes the distribution of species do not change by location. 

One common mistake in diet studies is the failure to insure that dietary treatments have the same caloric density (isocaloric) or the same protein level (isonitrogenous) when they should.Thus, simply exchanging ingredients will change the energy level of the diet as well as the protein level and confound the experiment with an extra variable. Energy must be added to some of the diets to make them isocaloric.

The same principle can be applied to experiments that include diets with different protein sources as dietary treatments. In this case, care must be taken to make sure that the growth effects being measured are due to protein source rather than protein level. The diets are made isonitrogenous by varying the level of the protein sources according to the protein content of each

Feeding Plasticity and Nutritional Physiology in Tropical FishesReview Article

Fish Physiology, Volume 21, 2005, Pages 155-224

Konrad Dabrowski, Maria Celia Portella

It depends on the concentration.

I'm agree with Gideon Khoo.

You may ask Dr. Lyudmila Litvinenko g-r-c[@]mail.ru from the Laboratory for commercial invertebrates of the Fisheries Center (Tyumen, Russia) 

This Center has experience on your question in relation to Gammarus lacustris

Please refer to Hyslop (1980) and Chipps and Garvey (2007) to help point you in the right direction.  Volumetric analyses are, in my opinion, more difficult than using wet or dry weights.  However, volumteric analyses are somewhat better than weights in certain situations (e.g. Performing SCA while at sea).  Ultimately this is up to you, but most people today use weight data for its ease of use and direct application with other weight-based research efforts (e.g ecosystem based modeling, individual consumption estimates,  bagged classification tree analyses, etc.)

sounds like a very cool project. I have only done work with SEM. Is there any reason you can't use SEM? Erik Zettler took some great pictures while mapping out the microbial community on plastics found in a variety of marine environments. I assume that you will supplement the images with spectroscopy. This article discusses methods for that as well. Hope this helps even a little bit! 

You can use endogenous or internal markers which are naturally available in the feed such as: ash, crude fiber, cellulose and hydrolysis resistant organic matter. You only need to determine one of these internal indicators in the feed and fecal, then use the formula according to Cho and Slinger (1979) for calculating ADC. For more information please find attached file.

ADC (%) = 100 – [100 × (marker in diet / marker in faeces)] × [(% nutrient in faeces / % nutrient in diet)]. 

Cho, C.Y., Slinger, S.J., 1979. Apparent digestibility measurements in feed stuffs for rainbow       trout. In: Halver, J.E., Tiews, K. (Eds.), Finfish Nutrition and Fish feed Technology, Vol.     2. Heinemann, Berlin, Germany, pp. 239–247.

Best regards

Mansour

Thank you all. You will see my paper very soon.

Dear Wolf-Dieter N Busch,

Since we have focused on thiamine deficiency in the ecosystem for a number of years now, I would like to say that we do not know the background to the ongoing deficiency. Yes, there is a number of working hypothesis published, although if there is a common cause to this deficiency, we still do not know its common background. This is substantiated by the simple fact that many bird species, aquatic and "terrestrial", are affected nowadays, please see attached article. Furthermore, we want to stress that thiamine deficiency is a underestimated problem in our ecosystems.

Very best regards

 Lennart Balk

References

1.       Soltan, M. A., Ibrahim, M. K. Fatma A. Hafez and Fath El-Bab, A. F. (2001): Effect of partial and total replacement of fish meal by soybean meal on growth and proximate analysis of Nile tilapia (Oreochromis niloticus). Egyptian J. Nutrition and Feeds 4 (Special Issue) :799-812.

1.       Hassaan, M. S. Soltan, M. A. and Abdel-Moez, A. M. (2015): Nutritive value of soybean meal after solid state fermentation with Saccharomyces cerevisiae for Nile tilapia, Oreochromis niloticus. Animal Feed Science and Technology, 201:89-98.

What I am going to say is the most classical approach to quantify feeding on a resource by animals.

So, per capita ingestion rates should depend on two factors:

1. The species of larval fish, which determines, for instance, an intrinsic attack rate

2. The density of a resource, for instance, zooplancton, that larval fish feeds on.  Per capita ingestion rates should increase with resource availability.  However, it is reasonable to assume also that, when resource availability is very high, per capita ingestion rates should level off and reach some asymptotic value.

These two assumptions brings us to the famous Holling II type functional response. This is a two parametric function that has been fitted to data quite often since Holling paper:

C. S. Holling (1965). The Functional Response of Predators to Prey Density and its Role in Mimicry and Population Regulation. Memoirs of the Entomological Society of Canada, 97, pp 5-60. doi:10.4039/entm9745fv.

Since I am not an expert in larval fish feeding, my answer may sound very basic to you. However, let me say that whatever we try to do, it is very nice and fair to look always for connections to classical work. If this answer ends up not being very useful to you, it will be at least an acknowledgement to one of the classics in Ecology.

I think you need to consider about the feeding behavior of both

Hi Jude,

B. circulans may be the act as good probiotic by the nature of hydrolysis of starch, gelatin, beta galactosidase etc... hence the Leucaena leaf meal inoculated with B. circulans is good probiotic nature than the gut isolated B. circulans due to poor decomposition of casein.

I appreciate the answers I have received from each of you.  Thank you!  My problem is, I haven't the means or the money to analyze Chlorella vulgaris samples for their carotenoids.  I am looking for the average relative amounts of each of the individual carotenoids of C. vulgaris, and was hoping that some of you had done work that you could tell me about.  As to H. pluvialis, I am already planning on adding natural astaxanthin to the feed.

I understand that C. vulgaris may contain canthaxanthin, a carotenoid I am hoping to include.  Does anyone know if all strains carry it, and in what relative amounts?

In my point of view, salinity greatly affects taurine synthesis. CDO and CSD are key enzyme catalyzing taurine production in animal liver. You may need to look at the availability of other molecules such as B12 and serine (for example) on taurine synthesis. I am not experienced enough about taurine receptors, unfortunately.

Some times government quality control officer visited our fish processing industry once or twice in a month; they usually defrost our frozen processing sea-food. Defrost, frost in once, it might be OK to avoid shrinkage; but more than once it might be caused for shrinkage. Controlling of temperature during transportation is the helpful for avoiding shrinkage. I am referring the HACCP manual which means Hazard Analysis Critical Control Point. 

I have attached herewith one paper for your information.

one major negative effect could be social acceptance. Maggots are produced from rotten carcass and this usually  are very malodorous.Besides bacteria may be transferred when maggots are harvested  washed and fed fresh. Consumers that are unaware  may pose no problem. There could be possible pathogen transfer to the fish and fish hygienic welfare may be compromised.However in most cases maggot meal are made from dried out maggot that gets ground to dust.The maggot meal are now used. The heat of drying may  reduce bacteria infection maybe to some extent.

It is completely depends on fish species. Fish that find their food by olfactory and gustatory system, such as sturgeons, catfish and common carp, has great response to certain attractant, especially dispensable amino acids. There are many literature on this topic. Be careful, if the basal diet contains high levels of fish meal, usually no needs for attractants. You should apply attractants in non-fish meal based diets such as soy-, soy concentrate-, meat meal-, gluten- and casein-based diets.

Good luck

Thank you all for your reply. Will definitely stop feeding Liquifry.

Use 

Hola!! Aca en la UNA, el compañero Adrian Sevilla (Estación Experimental 28 Millas, Limon) ha tenido experiencias de producción. Hicimos varios levantes de semilla con los colegas de la Universidad Autonoma de Juarez, Tabasco. Además, el colega Maurizio Protti tambien participo en los levantes aca en CR, aunque ahora el esta pensionado.

Saludos

Visceral somatic index, as I used to Pantanal fishes was calculated as viscera weigh (that means all viscera including also fat deposits in the viscera that is very high as a result of fish feeding  and accumulation during the flooding period). In catfishes, they have also a exclusive fat deposit in the abdominal cavity that has no similar in scale fishes. So, visceral somatic index is very important as we consider that a lot of Pantanal fishes do migration to headwaters for reproduction. If they don't have enough fat deposit (that can be measured as visceral somatic index), they doesn't do upstream migation for reproduction.

please follow the link. http://www.allaboutfeed.net/Nutrition/Research/2012/2/The-better-the-pellet-the-better-the-performance-AAF012746W/

How much do u need? A thousand tonne so that I can ship for you the cheapest one

I agree with Mr Marudhupandi explanation. There is certain limit for fish to accept optimize dosage. As far I know, Marine fish more tolerate to high dosage of omega 3 rather than freshwater. But the point is how efficient fish could absorb it or digestibility to the fish.... i guess...

Dear Dr. Keramat

I far as i Know, there were some research project in Tarbiat Modarres Univ or Caspian Ecology research center,

Good luck

You should be looking at the potential (ovarian) versus the actual (berried) fecundity, the latter being the number of eggs that are actually carried. I think it is important to compare at least 20-30 individuals throughout a size range, as egg carrying capacity would be expected to increase with size. A paper below has some methods.

You can put the mixture in a gelatin capsule.

Thank-you. I have tried simliar methods without sucess but this gives me more information to work out the method.

I have developed a function. It also provides useful results. I've tested this feature on only one data set and I did not yet published it. It looks as if we are working in the same field

Normally you would look to grow the fish until they have at least doubled in size - so this is affected by the starting size of the fish. Time is not so important as the use of the nutrients by the fish to grow. Doubling, tripling or more in size will show if nutrients are limiting or not.

Rotifers are fed at a rate of three to five rotifers per ml until larval fish can consume larger foods at about day 11 post-hatch. Larval mullet ( Mugil cephalus ) require a food density of 10 rotifers per ml, when there are 25 to 50 larvae per liter, through day 40. Once rotifers are harvested from the culture system food is often limited, so the nutritional value of rotifers decreases over time. It is best to feed them to fish at least twice a day, or replenish them whenever rotifer density drops below a des- ignated number per ml. For exam- ple, in red drum larval culture, replenishment should occur when rotifer density drops below 3 per ml. Since one fish larva can eat as many as 1,900 rotifers per day, from 13,300 to 57,000 rotifers are needed to feed one fish larva through this period (depending upon fish species and rotifer size). Most producers estimate three times the amount of rotifers actually eaten (1,900 X 3 = 5,700 rotifers per day) are fed per larva. Therefore, as many as 39,900 rotifers (for a 7-day period) to 171,000 rotifers (for a 30-day peri- od) may be required to feed one fish larva. Feeding too few rotifers often results in slow growth and too much size variation; feeding too many rotifers can cause the fish to ingest so much that assimi- lation becomes a problem. For most marine finfish species being reared indoors, the weaning of larvae from live rotifers and Artemia to dry food should begin well in advance of the transfor- mation from larvae to juveniles. This transition might be timed to take 3 days or as long as 2 weeks, but should be done gradually. Food particles should be the largest that can be swallowed easily by the fish (one-fourth to one- half of mouth width). Starter feeds should contain 50 to 60 percent high quality protein. As an exam- ple, in the past red drum larvae were generally fed rotifers from day 3 post-hatch to day 11, Artemia nauplii from day 11 to 21, and then weaned onto dry feeds. More recent protocols include the co-feeding of micro-particulate larval diets starting at day 5. Although live zooplankton is still used, dependence on them as the sole nutrient source has been significantly reduced, and the need to wean the animals from live foods is eliminated.

Artemia nauplii are maintained in the larval culture tank at densities of 0.5 to 2 per ml for most species of finfish and up to 6 per ml in the more advanced larval shrimp stages. To estimate the amount of Artemia required one must consider both the volume of the tank and the expected number of Artemia the larvae will consume. Based on the stage or the age of the larvae, estimate a daily Artemia requirement per ml. This feeding rate can be adjusted slightly, depending on the stocking density (number of target larvae per litre) and the rate at which the Artemia are consumed. The total requirement is then calculated by multiplying the predicted requirement per ml by the total volume of the rearing tanks. Each gram of cysts contains approximately 200,000 to 300,000 cysts. Artemia generally have at least a 50 percent hatch.