The Continuing Demand for Sustainable Fishmeal and Fish Oil in Aquaculture Diets

A highly interesting article, it is true fish meal has become indispensable ingredient in fish diets. Many efforts have been done to replace the fish meal, but in vain as it contain certain unidentified growth promoting factors. Fish proteins are easily digestible and cause less impact on the water quality as against to plant proteins. The usage in marine fish farming, crustacean nutrition and salmon and trout farming is really alarming.

The future of aquaculture depends upon reduction in utilization of fish meal and reduction of pressure on forage fisheries. Aquaculture is growing rapidly and this growth cannot be sustained without incorporation of adequate amount of plant protein as substitutes of fish meal. Fish meal utilization has very good growth implications but recent researches have shown that it is not as important. It has been reduced considerably by series of plant protein sources and this trend will continue. Fish meal is the source of environmental pollutant like phosphorous that causes eutophication and enrichment. There is global tend towards environmental conservation preservation and green revolution. Fish farming has been accused of negligence and source of pollutant in the ecosystem. The reduction of fish meal will alleviate this snag while enhancing profitability and sustainability of the aquaculture industry. It s important that more efforts and resources be directed to wards finding more alternatives to fish meal in aqua feed. I am presently carrying out a research in this direction for the African catfish Clarias gariepinus.

This topic is really relevant, fish meal and fish oil has become indispensable. In my commercial extruded diets, I have been using vegetable protein with fishmeal at about 15% but we found out that the rate of acceptability is low compared to fish oil coated feeds which are imported.Fish oil is not available in our country so we are forced to use veg oil. The feeds are for African clarias garienpinus. I will really appreciate if any body has solutions to increase the acceptability with the use of local available materials-veg oil. May be an attractant ? Thanks

Most of the plant ingredients used in fish feed formulations contain phytates and phytic acids that contain high amount of phosphorus locked up in them. This phosphorus can be extracted up on involvement of enzyme phytase. This enzyme is not produced by the fish and thus phytates and phytic acids enter the pond ecosytem which are in turn degraded by the action of enzyme phytase produced by the microbes releasing phosphorus into pond system thus leading to pollution. If phytase is incorporated in the fish meal diets then it results in phosphorus retention in the body of fish, thus reducing the load of phosphorus in to the pond system. The fish feed industry has already considered incorporating the phytase enzyme in their commercial formulations. Our experiments with incorporation of microbial phytase at 1% has shown reduced levels Ammonia, Nitrite and Phosphorus in water as against to control.

Fish meal is the skeleton of dietary formulation in fish feeds, it is also added to face fish species nutrients requirements especially EAAs, EFAs and inturn phospholipids.
So, Fishmeal must be investigated to be adjusted at the exact fish species requirements to provide expenditures could be excess of fish needs. This requirements indeed vary according to fishmeal type, source and manufacture.
In that respect, and because physiological condition of fish depends mainly on genetical, environmental and nutritional factors; requirements vary. accordingly, trials must be carried out in order to draw species specific requirements under different conditions using different ingredients to build species nutritional data base. (Nikolesky, 1961).

Fish meal is a good source of protein and its have some unidentify essential factors which can improve the growth fastly. To be use of fishmeal it is very much important to select the good quality fishmeal to be free from salmonella.

Do you have any idea if the the fish meal feed industry are already using phytase in their formulation?

Thank you very much for your information.
Do you think that the feed industries use the same phytase in fish than in pigs and poultry or other adapted to lower temperatures?

I do not know about the type of phytase that is being employed in the fish feed industry. But it is worth for use in tropical fish diets. However, when it comes to temperate fish diets and use of phytase, I am unware of its efficiency. If the phytase is to be active it is the pH that is imporatant and hardly any difference exist between the phytase manufatured by dffferent companies. Some are active at wide rane of acidic pH while other at narrow range of acidic pH.

Yes, I too echo with the benefits of enzyme applications into aquaculture feeds. The enzyme efficacy & consistent performace depends on the technology on which it is produced and its temperature resistence (Feed process) & pH tolerence. Alltech's Allzyme SSF is a complex enzyme, produced under solid state fermentation method and we guarantee for seven enzymes but there more than hundred enzymes!!!!!. SSF has been proven very effectively that the performance of fish in low fish meal based diets and high fish meal diets are same. And we have noticed that there is significant reductions in the FCRs in the low fish meal inclusion diets upto by 13% reductions in FCR and 10% increase in the ABW. India is witnessed with a lot of extruded fish feed mill and extrusion itself provide some space to go upto 8 to 9% though process technology may not interfere at this level but fish might encounter problems of poor digestion. In these conditions enzyme application is a perfect way to make use of that opportunity.

And please keep in mind, as one of the previous speakers mentioned, the necessarity to keep a certain acidic pH when working with phytases. It had been several times documented in livestock, as well as recently in aquaculture (trout) at the University of As in Norway that the combination of acidifier and phytase act synergistically in improving performance parameters of fish. The use of organic acids in aquaculture has anyway lately gained interest, as the increasing amount of publications show. And again... as discussed a while ago, the use of acidifier in fish diets shows next to the effects on performance and bacteria promising results on digestibility - among them protein (nitrogen), calcium and phosphorus... thus coming back to the original topic of this forum:-)... sustainability.

Fishmeal and fish oil have been and will continue to be vital ingredients in many types of aquaculture diets. Although supplies are likely to remain tight the various sectors of aquaculture will be able to grow by complementing the marine ingredients with ingredients from other sources and this will result in lower inclusion levels of both fishmeal and fish oil.
Now there are many alternatives for fish meal to be used in the aqua feed such as algae and some plant proteins with supplements.
Algae is a good alternative source for fish meal in aqua feeds, One fundamental consideration is that algae are the base of the aquatic food chains that produce the food
resources that fish are adapted to consume. But often it is not appreciated that the biochemical diversity among different algae can be vastly greater than among land plants, even when ‘Blue-Green Algae’ (e.g. Spirulina), more properly called Cyanobacteria, are excluded from consideration.
Fishmeal is so widely used in feeds largely thanks to its substantial content of high-quality proteins, containing all the essential amino acids. A critical shortcoming of the crop plant proteins commonly used in fish feeds is that they are deficient in certain amino acids such as lysine, methionine, threonine, and tryptophan (Li et al. 2009), whereas analyses of the amino acid content of numerous algae have found that although there is significant variation, they generally contain all the essential amino acids.