Feeds and feeding under semi-intensive rearing conditions in ponds
Nursery ponds
In Southeast Asia, Asian seabass are traditionally fed with chopped and ground trash fish fillets (4–6 mm3) (Kungvankij et al., 1985). Table 4 shows the most appropriate feed particle size relative to fish size. Trashfish flesh may be used directly or formed into balls for storage and may be kept in the refrigerator 2–3 days (Tiensongrusmee et al., 1989).
Another feeding technique involves the inoculation of ponds with Artemia. Two to three weeks prior to stocking, newly hatched Artemia nauplii are inoculated into the pond (1 kg of dry cyst/ha). Artemia will utilize the natural food as feed for growth and will reach the adult stage within 10–14 days. Another approach is to stock and grow Artemia nauplii in a separate pond from which Artemia adults can be harvested daily to feed the fry (Kungvankij et al., 1985).
Out-growing ponds
Under monoculture practices the production of Asian seabass is entirely dependent on exogenous feed, the quantities of which must be carefully monitored to avoid water pollution (Kungvankij et al., 1985). In Asia, Asian seabass is often produced in polyculture with a forage species, hence reducing the dependence on trash fish and/or pellets. The choice of forage fish depends on its ability to reproduce continuously in quantities sufficient to sustain the growth of seabass throughout the culture period. Moreover, the forage fish must be able to utilize natural food produced in the pond and should not compete for food with the seabass (Kungvankij et al., 1985). Tilapia species (Oreochromis mossambicus, Oreochromis niloticus, etc.) are often chosen as forage fish for Asian seabass culture in South-East Asia (Barlow, Williams and Rimmer, 1996).
Cost/benefit studies have revealed that seabass polyculture with tilapia or fed on trashfish is more profitable than monoculture using shrimp feed or moist formulated feeds (Corre and Hassan, 1995).
