Effect of stocking density on the survival and growth of tank-reared Deccan mahseer Tor khudree (Sykes, 1849)

Abstract

Deccan mahseer, Tor khudree (Sykes, 1849) is the most popular mahseer species of the Western Ghats. However, informationon optimising stocking density for fingerling rearing is not available for T. khudree. A study was undertaken to evaluate theeffect of stocking density on the growth and survival of the blue-fin mahseer, Tor khudree in fry to fingerling rearing. Fishwere reared for 90 days at stocking densities of 15, 25, 35 and 45 fish m-2 in soil-based 24 m2 masonry tanks. The tanks werefertilised initially with cow dung at 3 t ha-1 and were stocked with fry of T. khudree (mean length 1.31±0.09 cm; weight9.49±0.12 mg) after a week of manuring. A mixture (1:1) of powdered groundnut oil cake and rice bran was fed at 10% ofbody weight to the fish during the first month. Subsequently, fish were fed to satiation with a fishmeal-based sinking pelletedfeed (3 mm, 35% crude protein). The length of fish at harvest ranged from 5.03 to 6.43 cm and weight from 1.39 to 3.47 g.The mean final length, weight, specific growth rate and condition factor were the highest (p<0.05) under 15 m-2 and lowestunder 45 m-2 stocking density. The condition factor remained above 1 under all the treatments. No significant (p>0.05)difference in the survival of fish at harvest was recorded. Fish biomass estimates were higher (p<0.05) at higher stockingdensities. The similar (p>0.05) final length and condition factor between the stocking densities of 15, 25 and 35 m-2 and thehighest fish biomass at 35 m-2 indicate a stocking density of 35 fry m-2 as optimal for fry to fingerling rearing of T. khudree. Keywords: Blue-fin mahseer, Peninsular carp, Seed rearing, Stocking density