Optimum stocking density for Parachanna obscura larvae fed at its optimum ration

Abstract

Two experiments were conducted during 15 days respectively in re–circulating system composed of 15 plastic tanks containing 20L of water each. This study aims at estimating optimum feeding rate and stocking density for efficient growth, food utilization and survival rate of Parachanna obscura larvae (initial body weight = 0.1 ± 0.0 g and 0.15 ± 0.13 g). In the first experiment, five food rations (5, 10, 20, 25 and 30% of body weight per day) were tested in triplicate. Specific Growth Rate (SGR) and Feed Efficiency (FE) of larvae fed different rations varied significantly (P<0.05). Best SGR and FE were obtained with rations from 5 to 10% of body weight. Two mathematical models were used to analyse the relationships between feeding level and SGR. Optimum and maximum rations are 8.13% and 25% of body weight respectively. In the second experiment, five stocking densities (5, 20, 35, 50 and 65 larvae/L) were assigned in triplicate. Fish were fed manually with ration 8.13% of body weight. Results showed that SGR and FE obtained with different densities varied significantly (P<0.05). Highest final body weight and survival rate of fish were obtained with stocking density 20/L of water. Moreover, best SGR and FE were observed in larvae stocked at density 20 larvae/L (P<0.05). Thus, optimum stocking density of P. obscura fry (initial body weight = 0.15 ± 0.13 g) is 20/L.

Keywords: Parachanna obscura, rations, stocking density, growth, Feed Efficiency