Live food
The most commonly used live feed organisms used to enhance growth and survival of catla larvae under tank culture conditions are Brachionus sp., Moina micrura, Daphnia carinata, Diaptomus sp., Mesocyclops sp. (Jhingran, 1991; Jana and Chakrabarti, 1990; Kumar et al., 2000; Sharma and Chakrabarti, 2003). However, it should be noted that under normal farming conditions larvae are reared in manured nursery ponds.
Formulated feed
Aquafeed production is a nascent industry in India and only a small proportion of carp farmers (8 percent) use industrially manufactured feeds (Veerina et al., 1993). Most farmers are reliant on and prefer to make their own and cheaper feeds. Despite the increasing demand for artificial feeds the availability of formulated commercial feeds for the various life history stages of Indian major carps remains a constraint throughout the subcontinent (ICAR, 2006). Formulated feeds have several advantages and disadvantages (Table 9).
Feed ingredients that are used or have the potential to be used as protein and/or energy supplement in catla feed are listed in Table 10. Formulated feeds used in semi-intensive and intensive culture of catla are summarized in Table 11 and Table 12. A basal diet for carp fry, containing 35 percent protein (from processed full fat soybean), has been recommended by ICAR (2006). Singh et al. (2004) showed that the use of this diet led to improve growth and survival of fry in comparison to the traditional mustard oil cake-rice bran based diet.
Several alternative protein sources can be successfully used for the preparation of catla diets. Amongst others these include fermented silkworm pupae silage, which results in higher survival, improved FCRs and specific growth rates in comparison to fishmeal based diets (Rangacharyulu et al., 2003). The incorporation of dry Spirogyra powder (40 percent) in catla fingerling feeds improves the protein and lipid content of the fish (Kumar et al., 2004). The incorporation of maize gluten (5 percent) in supplementary catla fingerling feeds may replace fishmeal by 25 percent without affecting the growth of fish (Kaur and Saxena, 2005) under pond culture conditions.
High energy carbohydrate feedstuffs such as Colocasia esculenta (15 percent) (Nandeesha et al., 1991) or cooked potato starch (30 percent) (Erfanullah and Jafri, 1998) can also successfully be incorporated into catla feeds.
Incorporation of soybean oil (2.7 percent) and fish oil (0.3 percent) in the diet of brood female catla (3.0 – 5.5 kg) for a period of 93 days results in improved reproductive performance such as advanced maturation, increased fecundity and significantly higher fertilization rates of eggs (Nandi et al., 2001). Pellet feeds containing 30 percent crude protein, 20 percent carbohydrate and 7 percent fat, complemented with vitamins and minerals of up to 2-3 percent are recommended for brood fish (Bakos, 2001).
Soybean meal supplemented with methionine, lysine (0.4–0.5 percent), oil (10 percent) and vitamins and minerals may totally replace fishmeal in practical feeds for on-growing of carps. Mustard and rapeseed oilcakes may be used up to 35 percent and 24 percent, respectively along with other plant materials in carp diets (ICAR, 2006).
Despite the current body of knowledge with respect to the nutritional requirements of catla there are no specific commercial feeds for this species. The feeds that are available are used for most carp species in India. The proximate composition of factory-made carp feeds is 20-30 percent protein, 2-4 percent fat, 10-15 percent fiber, 30-40 percent carbohydrate, 8-10 percent ash and normally the feeds are supplemented with lysine, methionine, vitamins and minerals (www.fao.org/DOCREP/003/V4430E/V4430E05.htm). The binders used in the manufacture of carp feeds are summarized in Table 13, while Table 14 and Table 15 summarize the vitamins and minerals that are incorporated into the feeds. Figure 5 shows a commonly used manual feed making machine and the final sun dried product.
