Ongoing research uncovers opportunities for soybean protein concentrate to serve as a sustainable replacement for fishmeal for many aquaculture species. Research projects like this one for pearl gentian grouper, a hybrid species with high protein requirements, help determine where soy fits well. Initial results for this species show inclusion levels should be kept below 30%, but that soy can play a role.
Soybean meal is one of the most suitable alternatives to substitute for fishmeal in aquatic animal feeds due to its high protein content, good balance of essential amino acids (EAA) and lower cost. Soy protein concentrate (SPC) – made by moving a portion of the carbohydrates (sugars) from dehulled and defatted soy flakes through aqueous ethanol – has similar content of crude proteins and essential amino acids compared to fishmeal, along with lower anti-nutritional factors.
Several studies have assessed the influence of SPC on fish during the past 20 years, and results showed that different species have unequal levels of tolerance for SPC. Research has shown that SPC can effectively replace fishmeal as a protein source in the diet of some commercially important fishes like Atlantic salmon, rainbow trout and pompano, while other species only tolerate some levels of SPC.
The pearl gentian grouper – a hybrid species (Epinephelus lanceolatus ♂ × E. fuscoguttatus ♀) – is an important commercial fish that grows rapidly, has strong disease resistance and is highly nutritious.