TOTAL SULPHUR AMINO ACID REQUIREMENT OF FINGERLING CHANNA PUNCTATUS (BLOCH) BASED ON GROWTH, PROTEIN RETENTION, ENERGY RETENTION EFFICIENCY AND CARCASS COMPOSITION

Channa punctatus, commonly known as spotted murrel or soli, is a highly priced, commercially important tropical freshwater food fish. It is found to be distributed throughout the south-east Asian countries and is a natural inhabitant of stagnant muddy pond waters, paddy fields, weedy derelict swamps, beels, canals and reservoirs. This fish is considered to be hardy due to its tolerance to the extreme environmental conditions, crowdedness and diseases and is well known for its taste, high protein content, low intramuscular spines, high nutritive value, recuperative and medicinal qualities. Although, the complete information on protein requirement of C. punctatus is available, no information is available on optimum dietary amino acid requirement. Hence the present study was conducted to determine the optimum dietary total sulphur amino acid requirement of this fish.

A twelve-week feeding trial was conducted in thirty 70-L indoor tanks (water volume 55 L) provided with a water flow-through system (1-1.5 L/min) to optimize dietary total sulphur amino acid (TSAA) requirement in the diet of fingerling Channa punctatus (10.25±0.06 cm; 8.15±0.39 g). Six isonitrogenous (45% crude protein) and isocaloric (18.39 kJ/g gross energy) amino acid test diets containing casein, gelatin and crystalline L-amino acids with graded levels of methionine (0.56, 0.81, 1.06, 1.31, 1.56 and 2.06% dry diet) were formulated.  The diets were hand-fed to triplicate groups of fish to apparent satiation three times a day at 08:00, 12:30 and 17:30 h. Absolute weight gain (AWG), feed conversion ratio (FCR) and protein retention efficiency (PRE)  improved with the incremental levels of dietary TSAA from 0.56% (D1) to 1.31% (D4) and then plateaued. Based on growth performance (Table 1)  optimum dietary total sulphur amino acid requirement is recommended at 1.31% dry diet for fingerling C. punctatus.