Growth and feed utilization of juvenile tench (Tinca tinca L.) given diets in which soy protein concentrate replaces fishmeal and methionine and arginine are used as amino acid supplements

Abstract

ABSTRACT A 90-day experiment was conducted with four-month-old juvenile tench to test seven diets differing in replacement level of fishmeal (FM) by soy protein concentrate (SPC): 0% (control diet), 45%, 55%, 65%, 75%, 85% or 100% corresponding to 0, 312, 383, 451.6, 521.7, 590 or 695 g SPC kg−1 diet, respectively. Methionine and arginine supplementation was included from substitution levels of 55% and above to reach similar values to those provided by the control diet. Survival rate was close to 100%. The highest total length (TL) and weight (W) were reached with the control diet without significant differences from 45% to 55% diets. Significant lower TL, specific growth rate and daily increment in total length were obtained with 65% or higher replacement levels. The percentages of fish with externally visible deformities ranged from 0% to 9.3%, being higher with 75%, 85% and 100% replacement diets.