Preliminary studies on the conversion of Tubifex tubifex as food by elvers of Anguilla nebulosa (Gray and Hardwicke)

Elvers of Anguilla nebulosa were reared at 23°C in confined waters and their food intake, growth and conversion efficiency (K₁:%) were studied. Elvers weighing 278.33±14.35 mg were fed on an ad libitum diet of the oligochaete worm Tubifex tubifex for 60 days. On an average, the test individuals consumed 99.55±19.81 mg food/elver/day amounting to 35.76% of the initial biomass; during the corresponding period the elvers exhibited a growth rate of 5.03±2.42 mg gain in weight/elver/day which is equivalent to 5.06% of the consumed food. Thus the 'housekeeping' of these elvers may be regarded as established. In 50 days, the food required amounts to 0.358±50 = 17.90 times the initially stocked biomass. That is, 1 kg of initially stocked elvers may need 17.90 kg of T. tubifex to produce 0.912 kg of elver meat. A poor conversion ratio of 20 : 1 may be one reason for the slow growth of the elvers.