In a well fertilized pond, grey mullet fry and fingerling can find enough food for their growth but supplemental feed may also be distributed. Because of its low position on the food chain, mullet readily accept inexpensive supplemental feeds such as plant origin milling by-products and feeding ratio usually range between 5 and 10 percent BW/day.
Thus, Eissawy et al. (1974) obtained a daily weight gain of 0.45 g per fish with the fish fed at 10 percent BW/day on a mixture of cottonseed meal and rice bran (1:4 ratio) for 400 days. James et al. (1985) used rice bran and groundnut cake (1:1 ratio) at 5–10 percent BW/day. Other foodstuffs used in mullet feeding have been reviewed by Brusle (1981) and are presented in Table 4.
Mullets are capable of assimilating urea because of their intestinal bacterial activity, and it can therefore be incorporated in the diet (Brusle, 1981). M. cephalus can also consume large quantities of decayed plants and washed ashore plants can be collected to be used as supplemental feed (Brusle, 1981).
Formulated feeds (Table 8) and commercial pellets intended for others species such as pig and poultry are also often given. The feeding ratio is then approximately of 3 percent BW/day.
Abdelghany et al., (1995) reported that M. cephalus have a higher weight gain if fed with an artificial diet at 3 percent and 5 percent BW per day with a FCR of 3.6 and 5.6 and a protein efficiency ratio of 79 percent and 51 percent respectively (Table 8). However, they also showed that the fish fed with an artificial diet had higher fat and lower protein contents compared to those fish fed only on the natural food produced by the pond’s fertilization. Essa (1996) used an artificial pelleted diet containing 27.9 percent protein at the rate of 3 percent BW/day, six days a week.
In China, soybean milk is sometimes given as first supplemental feed in fertilized larval rearing ponds for Mugil so-iuy. Then paste made from soybean or peanut cake is distributed when fish can already swim in schools (Zheng, 1987).
Chow (1982) reported that fingerlings can be fed on finely ground cereal grains and mill by-products such as rice bran and groundnut oilcake.
Polyculture
Flathead grey mullet is commonly cultured with tilapia and carp in Egypt, Israel and Taiwan, and with prawns in India (James et al., 1985). In Taiwan, farmers often let the mullet feed on what is left over by other species and rice bran is occasionally given (Liao and Chao, 1991).
Nile tilapia and flathead grey mullet have been cultured in cages placed in fertilized ponds while the growth rate and the total production were not affected by this mixed culture (Essa, 1996). However, Cardona et al. (1996) showed that M. cephalus significantly feed on large zooplankton and chironomid mideges, which affect the growth performance of common carp and tilapia despite the overall increase in fish yield.
In abalone tank culture, the introduction of flathead grey mullet was reported to have a positive effect on decreasing biofouling (Swart et al., 2001a).
