Variation in food consumption, growth, and growth efficiency among juvenile hybrid sunfish held individually

Abstract

Daily food consumption, growth, and gross growth efficiency (GGE) were studied in juvenile hybrid sunfish (female green sunfish, Lepomis cyanellus×male bluegill, Lepomis macrochirus) fed ad libitum and held individually for 112 days. There were substantial inter-individual differences in food consumption; mean specific daily ration differed significantly ( P<0.01) among individuals, and cumulative consumption differed up to four-fold. Specific growth rates differed more than three-fold among individuals, and GGE differed by a factor of two. Consumption, growth, and the GGEs of individual fish were significantly correlated with their initial body weights ( P<0.05). Together, these results suggest that more attention should be given to inherent variation among individuals and that there may be a potential for reducing inter-individual variation and improving the growth of hybrid sunfish in aquaculture by removing small fish early in grow-out.