Performance of largemouth bass Micropterus salmoides (Lacépède, 1802), fed fishmeal-and fish oil-free diets

Abstract

Diets were manufactured for largemouth bass (LMB) replacing fishmeal (FM) with poultry by-product meal (PBM), soybean meal (SBM), and a hydrolyzed soy meal. Experimental diets included a FM control (FMC), and three FM-free formulations containing equal amounts of PBM and SBM with fish oil (diet F2), Algal meal DHA (F3) or a soy protein concentrate (SPC). A commercial LMB diet was included for reference. Fish (n=20 per group) were randomly dispersed into one of 20 tanks with group weights of ±5%, and densities of 7.39±0.17 kg m-3. Tanks were maintained as a RAS (28.3±0.76 oC, DO2 at 7.7±1.19 mg L-1) and randomly assigned to one of the five diets (n=80 fish per diet). Animals were fed to apparent satiation 3x daily for 12-weeks. Groups were weighed every 3 weeks and feed consumption recorded for calculation of FCRs. At trial end all fish were weighed and measured individually and 3 fish per tank employed for various analyses and comparisons against pre-trial samples. At trial end no differences (P > 0.05) were observed between groups for growth, SGR, or condition. FCR differed between the commercial and F3 diets (P < 0.05). F2 fed fish had higher (P < 0.05) visceral fat than F3 fed fish. Survival was 98-100% across all groups. Results indicate that judicious dietary manipulations may allow elimination of FM from LMB diets without compromising overall performance.