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¹ Universidad de León, Facultad de Veterinaria, Dpto. de Producción Animal, Campus de Vegazana s/n, 24071, León, Spain DOI : 10.4194/1303-2712-v14_3_23 Viewed : 4376 - Downloaded : 5048 The aim of this study was to evaluate different replacement levels of fish meal (FM) by soy protein concentrate (SPC) on survival, growth performance and body composition of juvenile tench (Tinca tinca). A 90-day experiment was conducted with 5 month-old juveniles (31.95 mm total length, 0.396 g weight). Eight practical diets (50% crude protein) differing in the level of replacement of FM protein by SPC protein were tested: 0% (control diet), 25%, 35%, 45%, 55%, 65%, 75% or 100% corresponding to 0, 159, 222, 285, 348, 412, 475 or 634 g SPC kg-1 diet, respectively. Survival rate was 100% for all diets. Significant differences were not found (P>0.05) in growth values among 25%, 35% or 45% replacement diets and the control diet. At higher replacement levels (from 55% to 100%), fish had significantly lower growth (P<0.05). Fish fed from 0% to 45% replacement diets had significantly lower (P<0.05) feed conversion ratio and higher (P<0.05) protein productive value than those fed diets with higher replacement levels. The percentages of fish with externally visible deformities ranged from 1.1% to 4.4%. The relation among amino acid profiles of the diets, body composition, growth performance of juveniles and amino acid requirements of other fish species are discussed. Up to 285 g SPC kg-1 diet can be included in diets for juvenile tench without impairing growth performance. Keywords : Soy protein concentrate, juvenile rearing, practical diet, tench