Fish meal replacement by soybean meal in diets for Tiger puffer, Takifugu rubripes

This study investigated the effect of partial replacement of dietary fish meal (FM) by defatted soybean meal (SBM) on growth performance of the juvenile tiger puffer, Takifugu rubripes. Triplicate groups of juvenile tiger puffer (initial weight of 20.1 g) were fed one of five experimental diets which were formulated to replace FM protein by SBM at 0%, 15%, 30%, 45%, or 60% (designated as SBM0, SBM15, SBM30, SBM45, or SBM60, respectively). Although negative effects were observed with SBM45 and SBM60 after 15 weeks of feeding, up to 30% of the dietary FM protein was successfully replaced without significant growth depression. Hematocrit, hemoglobin, and plasma phosphorus concentrations exhibited the same trend observed in growth performance. Plasma triacylglycerol and total cholesterol of fish fed the SBM60 diet were significantly lower compared to those of fish fed the SBM0 diet. Hepatosomatic index significantly decreased as dietary SBM inclusion increased. Results indicated that at least 30% FM protein can be replaced in diets for the tiger puffer by defatted SBM with supplemental monocalcium phosphate and limiting amino acids, lysine, and methionine. Further study is needed to focus on a decrease in dietary taurine by FM replacement with plant protein sources.