• dietary requirement;
  • Indian major carp;
  • Labeo rohita;
  • nutrition;
  • sulphur amino acids

The quantitative dietary sulphur amino acid requirement of the Indian major carp, Labeo rohita (Hamilton), was determined by conducting a growth study. The experimental diets contained 400 g crude protein kg−1 from casein, gelatine and supplemental crystalline amino acids. Diets containing six graded levels of methionine (3.2, 6.5, 9.0, 11.5, 14 and 16.5 g kg−1) with a constant level of cystine (1.4 g kg−1) were formulated and fed to triplicate groups of Labeo rohita fingerlings twice a day to satiation for 60 days. The optimum dietary requirement for methionine was estimated using the break-point regression analysis at 11.5 g kg−1 of diet or 28.8 g kg−1 of dietary protein. Thus the total sulphur amino acid (Met + Cys) requirement was determined to be 12.9 g kg−1 of diet or 32.3 g kg−1 of protein. Higher survival, specific growth rate and food conversion efficiency values were observed for fish fed the diet containing optimum levels of sulphur amino acids.