PlanetCatfish.com

Abstract
Black collared yellow catfish,

Horabagrus nigricollaris

, an endangered endemic catfish of the River Chalakudy, Kerala, cherished by the locals is one of the most sought-after ornamental fish. Due to the limited range of distribution and rarity, H. nigricollaris needs to be conserved in situ. Captive breeding, embryonic development, nursery rearing, and restocking of the species were done for the first time ever as part of conservation efforts. A total of 10 breeding trials with a sex ratio of 1:1 was conducted between 2022 and 2023. Half of brooders spontaneously spawned after receiving an injection of WOVA-FH hormone (1.0 ml/kg body weight) with a latency period of 11.3 ± 0.37 h. Mean spawning fecundity was 1740 ± 193 with fertilization rate of 68.7 ± 2.4%, hatching rate of 71.3 ± 1.9%, and survival rate of 88.1 ± 3.2%. The fertilized eggs were adhesive and elliptical, golden yellow in color with a diameter of 2.1 ± 0.02 mm. The first mitotic cleavage occurs at 35 min post-fertilization (pf) and morula, blastula, and gastrula stages were completed at approximately 3.50 h, 6.15 h, and 10.30 h, respectively. The incubation period was 27 ± 3 h at a temperature between 26 and 28 °C. Newly hatched larvae were transparent and light yellowish, measuring 4.4 ± 0.2 mm, with a large oval-shaped yolk sac. Yolk absorption was completed within 3 days post-hatching. The larvae were fed a systemic and overlapping diet of live and artificial feed over 30 days, resulting in an average length and weight of 20.4 ± 0.2 mm, 1.3 ± 0.1 g, and a survival rate of 56.1 ± 3.2%. About 1500 fish of 120 days old with mean length 73 ± 3.0 mm and average weight 3.2 ± 0.2 g were reintroduced into the Chalakudy River at the Vettilapara region, which is the type locality of the species, to safeguard and increase the wild population.