2.3.2. Experimental design and fish rearing
After yolk absorption, the hatchlings were fed with cladocerans(Moina spp.) until 2 weeks of age when they reached a length of about 1 cm. Then they were transferred to fiberglass tanks (70 cm in diameter, 35cmwater depth) at a stocking density of 200 fry/tank with three replications and fed a commercially available diet (Charoenpokaphand Com., Ltd.) containing 25% protein. After 5 weeks of rearing, they were transferred to nylon-net cages (2 m×1.5 m, 1.0 m water depth) at 120 fish/cage with three replications and fed the same diet. Feeding was made to satiation twice a day throughout the experiment which is a normal practice in the catfish farms.