The nutritional requirements of M. rosenbergii have not been standardized, however during the last decade, knowledge on the nutrient requirements of the species has increased substantially (New and Valenti, 2000). Prawns are capable of digesting a wide range of foods of both plant and animal origin (Mitra et al., 2005). Characterization of the activities of the digestive enzymes in the alimentary tract indicates the presence trypsin, amino peptidases, proteases, amylases, chitinase, cellulase, esterases and lipases (Mitra et al., 2005). Nutrient requirements of different life history stages of M. rosenbergii are summarized in Table 1.

Diets with 35-40 percent protein, gross energy of 13.37 kJ/g diet and a protein:energy ratio of 30-31 mg protein/kJ are suitable for growth of M. rosenbergii in clear water systems that do not have any supply of natural foods (Balazs and Ross, 1976; Millikin et al., 1980). Freuchtnicht et al. (1988) suggested that the optimum protein requirement for freshwater pawn is 30 percent and Reed and D’Abramo (1989) estimated that the protein requirement of M. rosenbergii is greater than 35 percent but less than 38 percent. Many commercial feeds for grow-out contain 24-32 percent crude protein. Sarma and Sahu (2002) suggest that the proportion of animal to plant-based feedstuffs in the diet of M. rosenbergii should be 75:25 and Mitra et al. (2005) suggest that a protein/starch ratio of 1:1 results in better feed efficiency and growth.

Broodstock reared in ponds in which they have access to natural food (benthic micro- and macro fauna) require about 30 percent protein in the diet. M. rosenbergii requires the same ten essential amino acids as other crustacean (Watnable, 1978), but quantitative requirements have not been determined. The amino acid composition of the prawn muscle is used to provide guidelines in feed formulation (Das et al., 1996).

Larvae have a higher protein and lipid requirement than post larvae and on-growing prawns and are reared with Artemia nauplii containing 55 percent protein and 21 percent lipid (New and Valenti, 2000). Artemia nauplii are normally enriched with highly unsaturated fatty acids and other nutrients. Roustaian et al. (2000) suggested that the amino acid requirements of the freshwater prawn is relatively constant during all larval stages and can be satisfied by a protein that resembles the larval amino acid profile. The highest representation of the total amino acids were for glutamic acid and phenylalanine (with cystine) which ranges from 13.4–16.6 percent and 9.7–11.5 percent, respectively, whereas tryptophan (1.4–1.6 percent), methionine (1.4–2.7 percent) and histidine (2.9– 4.2 percent) were relatively lower (Roustaian et al., 2000).

The growth of postlarvae can be increased by the use of squid and squilla meal at 14 percent each in the diet (Naik et al., 2001). Under laboratory conditions the protein requirement of post larvae and juveniles is 30-45 percent (Rangacharyulu, 1999) and the optimum P/E ratio is reported to be 26.28 mg protein/KJ digestible energy (Balaji, Sahu and Tripathi, 2002).

Comparatively high specific activity of amylase in M. rosenbergii supports the suggestion that the species efficiently utilizes carbohydrates as a source of energy (Mitra et al., 2005). Moreover, Diaz-Herrera et al. (1992) report that carbohydrates are the principal substrates for energy production in larval and postlarval M. rosenbergii. Complex polysaccharides, including starch and dextrin, are more effectively utilized than simple sugars. Dietary glucosamine facilitates molting followed by enhanced growth (Mitra et al., 2005). Supplementing the diet with chitin either from shrimphead meal (natural source) or in purified form enhances the growthrate ofpostlarvae. Dietary protein is optimised at a dietary lipid-carbohydrate ratio of 1:2.5-1:4 (Sahu, 2004).

Because of the efficient use of dietary carbohydrate as an energy source, lipid levels in prawn diets can be as low as 5 percent. Quantitative lipid requirements range between 6-8 percent (Rangacharyulu, 1999; Tiwari and Sahu, 1999). Freshwater prawns can not synthesize 18:2n-6 (linoleic acid) or 18:3n-3 (linolenic acid) and hence are required in the diet (Reigh and Stickney, 1989). Both n-3 and n-6 HUFAs at dietary levels of 0.075 percent are known to increase weight gain and feed efficiency remarkably (Mitra et al., 2005). The dietary requirement for cholesterol is approximately 0.3-0.6 percent (Sahu, 2004). Unlike in penaeid shrimp feeds, there is no need to add high levels of purified cholesterol into freshwater prawn feeds, provided the ingredients contain sufficient levels of phytosterols (Mitra et al., 2005).

Higher levels of lipids and cholesterol are key factors in egg maturation and egg quality. Freshwater prawns have a limited ability to biosynthesize phospholipid de novo. A basal level of 0.8 percent dietary phospholipid is required to meet the demand of M. rosenbergii broodstock. Tiwari and Sahu (1999) reported that 5 percent soyalecithin along with 1 percent Cod liver oil was effective in promoting growth and survival of M. rosenbergii.

The vitamin requirements of M. rosenbergii are probably similar to other crustaceans. The require 60-150 mg vitamin C/kg diet. Levels of 60 mg ascorbic acid and 300 mg α -tocopherol per kg diet are considered sufficient for successful reproduction and larval viability. Manus et al. (2005) reported that vitamin C at 240 mg per kg reduces stress in freshwater prawns. It has been reported that vitamin E at 200 mg/kg diet modulated some of the antioxidants defense system by decreasing lipid peroxidation in the hepatopancreas (Mitra et al., 2005).

Information on the quantitative mineral requirements of freshwater prawns is limited. Dietary supply of calcium seems to improve growth. In soft water (with Ca levels of Ca. 5 ppm) performance is improved with a dietary supply of 3 percent calcium. The optimum dietary zinc level is 50-90 mg/kg diet (Mitra et al., 2005).