Optimization of induced breeding, embryonic development and larval ontogeny of Gangetic catfish, Mystus cavasius: evaluating the efficacy of exogenous hormones on reproductive performance

Abstract

Gangetic catfish, Mystus cavasius (Hamilton, 1822) is a commercially important freshwater catfish widely distributed in Southeast Asia. However, commercial farming of this species is hindered due to the unavailability of hatchery produced seed. To address this issue, two separate experiments were conducted. In the experiment one, three doses of human chorionic gonadotropin (HCG; 5, 10, and 15 IU g⁻¹) and commercial hormone (CH; 5, 10, and 15 µl g⁻¹) were administered to optimize the hormone dose for induced breeding. In the experiment two, mature brooders were induced to spawn using the optimum dose of CH (10 µl g⁻¹) to study the embryonic development and larval ontogeny. The results revealed that the optimum doses of HCG and CH were 15 IU g⁻¹ and 10 µl g⁻¹, respectively. Embryonic development showed the appearance of morula, blastula, gastrula, neurula, somitogenesis, and hatching at 1:20, 1:50, 4:55, 8:15, 10:05 and 16:30 hr post spawning (hps), respectively. Newly hatched larvae measured 2.339±0.210 mm in total length. Larvae were characterized by the presence of an oval shaped yolk sac (volume: 0.221±0.114 mm3) devoid of oil globules. Major morphological features observed during larval ontogeny include the formation of chin barbels, caudal fin rays, notochord, mouth opening and anal pore opening at 6 hps, 18 hps, 1, 2, 3, day post hatching (dph), respectively. The findings suggested that CH at a dose of 10 µl g⁻¹ and HCG at a dose of 15 IU g⁻¹ were the effective doses for induced breeding and seed production of M. cavasius.