The nutritional requirements of the various developmental stages of catla are summarized in Table 2 and Table 3. Gross protein requirements decease with increasing size. Larvae require 45 percent protein and 8-10 percent lipids and are able to utilize maximum of 26 percent carbohydrates. Larvae require 4 percent phospholipids and 150 mg/kg vitamin E for enhanced survival and growth (ICAR, 2006, Sinha and Sinha, 1994).
Catla fry also have a protein requirement of 45 percent, although under pond culture conditions this can be reduced to 35 percent (Singh et al., 2004). The total aromatic amino acid (phenylalanine plus tyrosine) requirement of fry is 4.70 percent of the dietary protein. In the absence of cystine, the methionine requirement of catla fry is 1.42 percent of the diet or 3.55 percent of the dietary protein. Excessive methione in fry diets results in lower growth (Ravi and Devaraj, 1991). This indicates a depressive effect of excess free methionine. Fry require an energy protein ratio of 8.0-8.5 (Singh and Bhanot 1988, Seenappa, 1992).
Catla fingerlings have a protein requirement of 40 percent (ICAR, 2006), although Seenappa and Devaraj (1995) have shown that feeding catla fingerlings (1.02 ± 0.03 g) with diets containing 30–35 percent protein, 4 percent fat and 35 percent carbohydrate results in a higher growth rate and better FCR. An E/P (energy: protein) ratio of 8.43 is required by catla fingerlings (Seenappa, 1992). Optimum dietary carbohydrate levels are 22-26 percent and should not exceed 30 percent (ICAR, 2006). Excessive dietary carbohydrate may cause metabolic stress and cellular changes (Yengkokpam et al., 2005).
Optimum protein and lipid levels for grow-out of carps are 30 percent and 7-9 percent, respectively (ICAR, 2006). Vitamin E should be supplied at the rate of 98.4 IU/kg dry diet for adults (ICAR, 2006). Commercial grade vitamin and mineral premix that are generally used in carp feed preparations should not exceed inclusion level of 2 percent for each (ICAR, 2006).
Broodstock require 33 percent and 14 percent crude protein and lipid, respectively (ICAR, 2006). The dietary supplementation of both n-3 (17 percent) and n-6 (24.4 percent) PUFA is essential to improve gonadal maturation, reproductive performance and spawning recovery in female catla (Nandi et al., 2001).
