Responses of largemouth bass ( Micropterus salmoides , Lacépède, 1802) to fishmeal‐, and fish oil‐free diets

Abstract

Largemouth bass (LMB; ~15.2 g initial weight) was fed one of the five experimental, and a fishmeal (FM)/fish oil (FO) control diet and two commercial (Xinxin, Coppens) LMB feeds for 10 weeks. Fish were dispersed into 24, 110-L aquaria (n = 20/tank) configured as a recirculating system. Aquaria were arbitrarily allocated to dietary treatments in triplicate (n = 60/fish diet). The FM component of experimental diets was replaced using poultry by-product meal and soy protein concentrate. One experimental diet contained FO, whereas in others, FO was replaced with canola, flax and/or algal oil or combinations thereof. At trial end, there were no differences among fish-fed various diets in terms of feed conversion or protein efficiency ratios. Weight gain and survival were similar for experimental groups, and LMB fed the Xinxin commercial feed, but the Coppens feed returned inferior (p < 0.05) weights and higher mortality. Condition factor, fillet yield and intraperitoneal fat ratios were unaffected by diet but hepatosomatic index varied. The Coppens feed caused greatest differences in whole-body protein, lipid and ash contents (p < 0.001). Whole-body fatty acid profiles reflected those of the diet, with algal oil enriched feed illustrating enhanced DHA:EPA ratios.