Short Communication: Stocking Density-Dependant Growth and Survival of Asian Sun Catfish,Horabagrus brachysoma (Gunther 1864) Fry During Hatchery Rearing

The present study was conducted to determine the optimum stocking density of Horabagrus brachysoma fry during fingerling production in the hatchery. For this purpose, four density levels (400, 800, 1200 and 1600 fry/0.6 m³) were considered. The experiment of fry rearing continued for a period of six weeks. The total length and wet weight of fry were significantly highest (P < 0.05) at 400 fry/0.6 m³ density compared to the other three density treatments during the entire rearing period. At harvesting, the length and weight of fry stocked at 1200 and 1600 numbers/0.6 m³ were similar to each other, and both were significantly lower (P < 0.05) than those of fish stocked at 800/0.6 m³. The decreased SGR, percent weight gain, and survival were also observed at the two highest density treatments. But the total biomass was observed to be highest (P < 0.05) at 1600/0.6 m³ density compared to those of the other three densities. If individual size and number of individuals for stocking are not constraints, the maximum number of surviving fry from a minimum rearing space was achieved at a stocking density of 1600 fry/0.6 m³ tank.     

Effect of dietary protein levels on growth,feed utilization and carcass composition of endangered bagrid catfish Horabagrus brachysoma (Gunther 1864) fingerlings

An 84‐day feeding trial was conducted to study the effect of different levels of dietary protein, 250 (P25), 300 (P30), 350 (P35), 400 (P40) and 450 g (P45) kg^?1 dry matter (DM) on growth, feed intake, feed utilization and carcass composition of bagrid catfish Horabagrus brachysoma fingerlings. Triplicate groups of fingerlings with mean initial body weight of 2.2 g were fed the experimental diets twice daily, till satiation, in 150‐L tanks supplied with flow‐through freshwater. Daily dry matter intake by the fingerlings decreased significantly (P < 0.05) when fed P25 diet, containing 250 g protein kg^?1. The highest body weight gain, specific growth rate (SGR) and protein efficiency ratio (PER), and the lowest feed conversion ratio (FCR) were observed in fish fed 350 g protein kg^?1 diet. The fish fed with P45 diet had the lowest (P < 0.05) carcass lipid content. The polynomial regression analysis indicates that H. brachysoma fingerlings require 391 g dietary crude protein kg^?1 diet.     

Larval Age at Stocking,Growth, and Survival During Fingerling Production of the Endangered Sun Catfish,Horabagrus brachysoma

An experiment was conducted to ascertain the initial rearing period required for Horabagrus brachysoma larvae before releasing them into the nursery tank for fingerling production. Hatchlings were reared for 7, 14, or 21 days in larval rearing tanks before stocking to nursery tanks. The 7-day-old larvae were significantly smaller at the end of the 2-week nursery rearing, but over the course of nursing, the 7-day-old larvae caught up to the 14- and 21-day larvae. The specific growth rate (SGR) of 7-day larvae was highest among the three treatments. However, mortality of 7-day larvae was the highest among the groups. Hence, it appears important to rear the larvae at least 2 weeks before stocking for fingerling production so as to increase survival rate.