Optimization of stocking density for Azolla based carp polyculture pond
Abstract, 2016, International Journal of Fisheries and Aquatic Studies
The study optimized the stocking density for Azolla based carp polyculture ponds under 3 different treatments like T 1 : 10000 fish ha-1 , T 2 : 11500 fish ha-1 and T 3 : 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-1 day-1 in all treatments) was applied as periodic fertilization. Water quality parameters (temperature, transparency, DO, pH, alkalinity and free CO 2) 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 were also evaluated. No significant difference in the mean values of water quality parameters were found among the treatments. Significant difference (P<0.05) with the treatments were found in all the growth parameters except survival rate. Treatment T 3 varied more significantly (P<0.05) for the mean values of total yield but in terms of total cost, gross benefit, net benefit, net profit margin and CBR, treatment T 1 (stocking density of 10000 fish ha-1) was found best. Findings indicated that the stocking density of 10000 fish ha-1 could be a good option for low cost Azolla based fish farming in Bangladesh.