A. K. Sahu

Larval survival and growth in Wallago attu (Bloch and Schneider): effects of light, photoperiod and feeding regimes

Abstract An in-door rearing study was conducted for 11 days with Wallago attu larvae fed on live zooplankton alone (control) or combinations of zooplankton and dry feed containing either fish meal (F1), meat meal (F2) or shrimp meal (F3) under 24 h continuous light (24L), 12 h light–12 h dark (12L:12D), 24 h red light (24RL) or complete darkness (0L). The percent survival of larvae was significantly different (P

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.

Recycling of the aquatic weed, water hyacinth, and animal wastes in the rearing of Indian major carps

Abstract The efficacy of recycling cattle wastes and the aquatic weed, water hyacinth, in the rearing ponds for Indian major carps was studied. No other input was provided. It was observed that addition of the weed alone (treatment A) increased fish production by about 52% as compared to the control (D) with no input. A combination of cattleshed washings and biogas slurry (treatment B) increased fish production by about 126% as compared to the control. A combined treatment with biogas slurry, cattleshed washings and water hyacinth (treatment C) gave the maximum production, about 170% higher than the control. The average gross/net productions obtained after one year of rearing for treatments A, B, C and D were 945 794.8 , 1409.5 1258.05 , 1679 1526.1 and 622 494.45 kg ha −1 year −1 respectively.

Evaluation of HCG-Delivery Systems and Levels on Spawning of Asian Catfish, Clarias batrachus (Linn.)

ABSTRACT An attempt has been made for multiple spawning of Asian catfish, Clarias batrachus, by sustained hormone administrations through injection and pellet at three different levels of human chorionic gonado-tropin (HCG): 150, 200, and 250 IU. The size of the eggs and biometry of larvae were significantly higher (P< 0.05) in hormone-treated females compared with untreated groups during first as well as second spawning. The administration of all three levels of sustained hormone was also influenced the rate of fertilization and hatching, which were significantly higher (P< 0.05) compared with control group. The total larvae produced by the fish at 200 and 250 IU HCG treatments during both the spawning operations was significantly higher (P< 0.05) than the other groups irrespective of the ways of administration. It was observed that the forms of sustained hormone had no variability on breeding parameters. But the fish can be bred prior to normal season by the use of sustained hormone and those can be again bred during the latter part of the season to augment the seed production.