Captive breeding of the stinging catfish, Heteropneustes fossilis (Bloch, 1794) found in Brahmaputra River, Assam, India using inducing agent ovasis and its early embryogenesis

Among the freshwater air-breathing fish of southeast Asia, Heteropneustes fossilis is considered to be a highly demanded, nutritious and popular fish species. This species was scrutinized in the current study and its embryonic and larval development was assessed.. In addition, the artificial dissemination of stinging catfish (H. fossilis) was carried out with different doses of the synthetic hormone ‘ovasis’. Fertilisation rate was recorded 75 ± 3.1% with a hatching rate of 57 ± 1.9%. Spawning was observed after 26- 30 hours of injection at 23 ± 2˚C. Fertilised eggs were found round in shape, transparent, non-adhesive and greenish in color, with a diameter of 0.8 - 1.0 mm. The incubation period of H. fossilis ranged from 27- 30 hours. The hatchlings were transparent and measured 2 - 3 mm in length, with an oval-shaped head bearing a green-colored yolk sac and a tail. An artificial diet containing 30% protein was supplied to the hatchlings at 5% of their body weight. The bulged yolk was dissolved slowly in successive days of development and completely disappeared on the 5^th day. At this stage, most of the larvae were surface dwellers and active swimmers.  Environmental factors such as temperature and hardness play a major role in the early development of this species. This study would provide new information which can positively affect the sustainable management and conservation of the species under study.