DIETARY PHOSPHORUS REQUIREMENT FOR HETEROPNEUSTES FOSSILIS BASED ON GROWTH INDICES HEMATOLOGICAL PARAMETERS AND CARCASS COMPOSITION

Heteropneustes fossilis, commonly known as Singhi is a highly preferred food fish due to its high protein and iron content. Its culture has gained attention because of its ability to efficiently utilize practical feeds and tolerance to adverse environmental conditions. Minerals are required for the normal life processes, and all animals, including fish, need these inorganic elements. The minerals are responsible for skeletal formation, maintenance of colloidal systems, regulation of acid-base equilibrium and for biologically important compounds such as hormones and enzymes. There is no information regarding phosphorus requirement of this fish. Hence, this study was conducted.

A feeding trial was conducted to determine dietary phosphorus requirement of fingerling H. fossilis (7.7 ± 0.2 g), casein-gelatin-based isonitrogenous (40% CP) and isoenergetic (14.72kJg^-1 DE) purified diets with seven levels of phosphorus (0.32%, 0.52%, 0.72%, 0.92%, 1.12%, 1.32% and 1.52% dry diet) were fed to triplicate groups of fish twice daily to apparent satiation for 12 weeks. Experiment was conducted in twenty one 70-L indoor tanks (water volume 55 L) provided with a water flow-through system (1-1.5 L/min). Incremental levels of dietary phosphorus from 0.32% to 0.92% significantly (P < 0.05) improved absolute weight gain (AWG g fish^-1), feed conversion ratio (FCR), protein retention efficiency (PRE), haemoglobin (g dL^-1) and haematocrit . Dietary phosphorus levels affected whole body composition. Whole body and vertebral phosphorus concentration increased with dietary phosphorus level from 0.32% to 0.92% (P<0.05) and then plateau over the level of 0.92% (P>0.05). Based on AWG, FCR and PRE dietary phosphorus requirement is found to be 0.92g/100g dry diet.