Cannibalism and survivorship of early juvenile African catfish Clarias gariepinus in relation to stocking density and 17β-estradiol treatment

ABSTRACT There were two stocking densities (i.e. 9,000 and 12,000 larvae m−2), two doses of 17β-estradiol and control without any hormonal treatment i.e. 0, 2.5, and 5 mg L−1. Hormone were given by immersing larvae in water for six hours to reduce cannibalism in African catfish larvae. Fishes were reared for 14 days intensively. The highest fish survival was at a stocking density of 12,000 larvae m−2 with 2.5 mg L−1 17β-estradiol. Cannibalism decreased at higher densities compared to the control. The level of 17β-estradiol in treated fish tended to be higher than that of the control group but the coefficient of variance decreased. At the end of rearing, the use of 17β-estradiol at higher densities improved the specific growth rate and relative body length.