Aquatic Animal Feeds

Aquatic animal feeds are specially formulated to ensure economically optimal aquatic animal growth. Feeds are increasingly being formulated to minimize environmental impact. These advances have resulted in the manufacture of feeds that are high in energy and nutrient-dense. This has resulted in improved feed conversion efficiencies (amount of feed to produce one pound of animal) and less waste discharge. This increased attention to feed conversion coupled with the fact that aquatic animals in general are far more efficient at feed conversion than terrestrial animals, has yielded conversions at nearly 1:1 in some species.

An important ingredient in some aquatic animal feeds is fish meal. Fish meal is produced from various pelagic fishes that, with some exception, are not normally consumed by humans. The fish that are caught to produce fish meal (menhaden and anchovy) are subject to quotas. Quotas are imposed by government agencies to ensure that fish stocks remain sustainable. Additional fish meal is produced from the “by-catch” of the fishing industry. By-catch is unwanted fish that are accidentally netted or caught in the process of fishing for higher value fish than is usually intended for human consumption. Most of this by-catch is currently discarded back into the ocean. While these particular pelagic species are typically not consumed by humans, as a fish meal, they form a significant part of the diet of many different kinds of animals (terrestrial and aquatic) which become human food (Table 1).

Some (commercially grown) aquatic animals grow well with feeds based primarily on plant materials. Catfish feed, for example, contains only 3-5 % fish meal but considerable quantities of soybean meal. Tilapia are planktivores that consume single celled algae and do not require any fish meal in their diets. Bivalve mollusks are filter feeders that utilize the natural foods present in the environment for their sustenance. Because domestication of aquatic species and food technology is a relatively young science, feed optimization has yet to occur. Fortunately, considerable private and university research is underway to provide enhanced feeds for aquaculture species use.