The invention provides a composition for use in culturing aquatic animals that includes one or more β-aspartyl dipeptides, or oligomers thereof, or salts thereof, wherein each of said β-aspartyl dipeptides comprises a β-L-aspartyl moiety as the first amino acid residue. The invention further relates to use of this composition as feed or feed additive for aquatic animals and as a method for culturing aquatic animals.