World Aquacluture Magazine - September 2020

68 SEP TEMBER 2020 • WORLD AQUACULTURE • WWW.WA S.ORG Broodstock Management Maintenance of healthy broodfish is a prerequisite for successful seed production in captivity (Fig. 1). Stinging catfish reach maturity in the first year. Broodfish of 70-80 g (male) and 100-120 g (female), commonly preferred for breeding, are raised in cement ponds at 2/m 2 . This reduces difficulties in collecting broodfish from earthen ponds and facilitates easy maintenance of water quality through water exchange when required to improve maturity. Water quality was as follows: DO 5.2-5.7 ppm, CO 2 4.6- 5.8 ppm, pH 7.3-8.5, temperature 27-30 C. Often, hatchery owners collect broodfish from ponds and maintain them in nylon hapa nets fixed in the ponds. Also, some farmers purchase broodfish during monsoon months and keep them in big metal containers for breeding, a condition that invites breeding failure in many cases. Farmers formerly fed broodfish with ground low-cost fish or fishmeal mixed with groundnut oil cake or rice bran. However, better breeding performance can be obtained by feeding a compound pelleted feed made from a mixture of fishmeal, groundnut oil cake, soybean meal and rice bran, with vitamins and minerals, containing 33 percent protein, at 2 percent of body weight daily. Sexual Dimorphism Sexes can be externally distinguished only during the breeding FIGURE 5. Fertilized eggs and yolk-sac fry of stinging catfish. FIGURE 6. A paste of Tubifex worms for feeding stinging catfish fry after yolk-sac absorption. FIGURE 3. Intramuscular injection of stinging catfish broodfish with spawning hormones to induce breeding. FIGURE 4. Hapas in concrete tanks for stinging catfish spawning.