Optimization of stocking density for Azolla based carp polyculture pond

Abstract

The study optimized the stocking density for Azolla based carp polyculture ponds under 3 different treatments like T1: 10000 fish ha-1, T2: 11500 fish ha-1 and T3: 12500 fish ha-1. Fishes (Hypophthalmichthys molitrix, Catla catla, Labeo rohita, Cirrhinus cirrhosus, Cyprinus carpio, Ctenopharyngodon idella and Barbonymus gonionotus) were also grown for a period of six months. Mean initial stocking weight of H. molitrix, C. catla, L. rohita, C. cirrhosus, C. carpio, C. idella and B. gonionotus were 60, 65, 58, 52, 61, 70 and 22 g respectively. There were 3 replications for each treatment under this experiment. Liming (250 kg ha-1) and basal fertilization (cow dung: 1500 kg ha-1, urea: 60 kg ha-1 and TSP: 60 kg ha-1) were done for all the treatments. Triple Super Phosphate (TSP) (2.5 kg ha-1day-1 in all treatments) was applied as periodic fertilization. Water quality parameters (temperature, transparency, DO, pH, alkalinity and free CO2) were monitored fortnightly and fish growth parameters (weight gain and Specific Growth Rate (SGR)) were monitored monthly. Economics (in terms of total cost, gross benefit, net profit margin and Cost Benefit Ratio (CBR)) of fish farming was also evaluated. No significant difference in the mean values of water quality parameters was found between the treatments. The significant difference (P