Optimum Phosphorus Requirement of Heterobranchus Bidorsalis Using Purified Diets

The dietary phosphorus requirement of Heterobranchus bidorsalis fingerlings was investigated by feeding six purified diets containing varying levels of phosphorus inclusion within a range of 0.4 to 1.8% and control using casein and gelatin as dietary protein sources and dextrin as energy source over a 56 day feeding period. The experiment was conducted in a static rearing system consisting of 12 plastic aquaria of 70L capacity. Each aquarium was stocked with 10 fingerlings of Heterobranchus bidorsalis with initial mean weight of 3.33+ 0.02 g/fish. Each treatment had two replicates and fish were fed twice daily to satiation. The results of the study showed that the Mean Weight Gain (MWG) and Specific Growth Rate (SGR) were significantly highest (4.87±0.14; 1.71 ± 0.02) respectively at 0.7%P inclusion level. The Feed Conversion Ratio (FCR) and Protein Efficiency Ratio (PER) among treatments ranged between 1.10±0.05 - 2.80±0.01 and 1.20±0.0 – 2.70+0.14 respectively. Whole body calcium and phosphorus were significantly (p< 0.05) highest (6.54+0.01g; 2.75 +0.01g) respectively in fish fed diet with 1.8%P. That showed that body mineralization continue beyond the requirement for optimal growth. Based on observed growth performance, it could be stated that the dietary phosphorus requirement of Heterobranchus bidorsalis fingerlings was 0.7%P.