The effect of dietary n-3 LC-PUFA levels on growth, survival, and feed utilization in juvenile Totoaba macdonaldi

The n-3 LC-PUFAs requirement was evaluated for Totoaba macdonaldi. Four isonitrogenous and isolipidic diets were formulated to contain increasing levels of n-3 LC-PUFAs (0.4, 0.8, 1.0, and 1.4% of the dry diet) and fed to juvenile totoaba (1.5 g initial body weight and 47 mm initial total length) for 56 days. Growth, survival, fish whole body proximate composition, fatty acid profile, feed utilization, and condition factor were evaluated in triplicate groups. Growth in terms of final weight and total length of fish fed diets containing 1.0% n-3 LC-PUFAs resulted in significantly higher values (16.11 ± 0.38 g and 119.62 ± 1.81 mm, respectively) compared to other treatments. However, fish fed diets supplemented with 1.4% n-3 LC-PUFAs resulted in the lowest final weight and total length (12.34 ± 0.49 g and 110.13 ± 0.92 mm, respectively). There were no significant differences in percent survival (all treatments 100%) and condition factor among treatments. The recommended n-3 LC-PUFA level in the diet for juvenile totoaba to attain the highest growth, and survival, as estimated here for 1 g fish, is 0.92% n-3 LC-PUFAs of the diet. Additionally, feed utilization in terms of feed conversion rate was lower in fish fed the diet containing 1.0% n-3 LC-PUFAs compared with the other treatments (0.7 vs. 0.8, P