Feed intake maintained at 3% of biomass/day for the three diets at the difference with other species (red drum, rainbow trout, and striped bass) with up to 75% replacement of FM protein with soybean protein. A replacement of fishmeal with soybean meal for red drum juveniles (Davis et al. 2002) reduced the palatability of the feed. Provided that 20% poultry by-products meal was present, fishmeal was reduced to 5% of the diet and replacing it with solvent extracted soybean meal. A similar approach was reported on trout (Cho et al. 2001.) and a combination of soy concentrate and crude protein soya (P80) would overturn the problem of succulence of the diet in absence of regular fishmeal. On a 34% CP diet with protein supplied by soybean meal and fishmeal, diets containing only soybean meal protein were poorly consumed by red drum (Turano et al. 2002) which lost weight (Cuzón et al. 2002).
In an experiment with Atlantic halibut using three isonitrogenous and isocaloric diets containing 0%, 18% and 36% toasted full-fat soybean were prepared through replacement of fishmeal, wheat and fish oil. The researchers concluded that up to 36% toasted full-fat soybean meal may be replacement in the diets of Atlantic halibut without negative effects on growth, feed efficiency or intestinal morphology (Grisdale-Helland et al. 2002).