September 2, 2016

'Vegetarian' fish being developed in Japan

A "vegetarian" fish? This is what a Japanese researcher is working to produce-a fish that feeds on low- or non-fishmeal feed, The Fish Site reported.

This research project gains importance in the light of the dwindling supplies of anchovy, a major ingredient in the manufacture of fishmeal and fish oil.

Prof. Shuichi Satoh, of Tokyo University of Marine Science and Technology is trying produce vegetarian fish by changing the amount of taurine in their feed, according to the report. An amino acid, taurine is a derivative of sulfur-containing compounds such as methionine that plays important roles in digestion and neurotransmission. It is present in fishmeal but not in plant-based alternatives, such as corn and soy.

"Taurine is indispensable. For one thing, it makes the fish able to eat more, and improves weight gain and feed efficiency. Without it, fish tend to exhibit poor growth and green liver syndrome", Satoh said, according to the report. 

Satoh, in collaboration with Nagasaki Fisheries Research Station, is starting with yellowtail and red sea bream. He said the latter ate anything and grew bigger and faster than expected on a diet with little to no fishmeal.

On the other hand, the yellowtail grew normally with 30% fishmeal in their feed, but a taurine supplement was necessary. Satoh said that if the feed has 20% fishmeal, a taurine supplement is required. However, there were times when the yellowtail didn't eat the soybean or plant-based feed. They were, therefore, tricked with the use of bonito peptides, which make the feed taste like fish. Digestive enzymes were added as this feed is difficult to digest unlike plant-based feed.

"We're currently experimenting with all kinds of mixtures such as poultry meal, pork, chicken meal and feather meal", Satoh told The Fish Site.

Still, he believes that soybean- and other plant-based feeds are the most environment-friendly. "A lot of feed manufacturers still believe fishmeal is the best but because prices are rising they have no choice but to look into other alternatives. Japan's aquaculture still uses a lot of fishmeal but I believe that will change."