Alterations in growth pattern relationships and condition factors of Channa gachua (Hamilton) exposed to a common biofertilizer

Abstract

Alteration in the length-weight and breath-weight relationship, as well as the condition factor of Channa gachua, was analysed after short-term (24, 48, 72 and 96 hours) and long-term (15, 30, 45, 60 and 75 days) exposure to the sublethal dose of 253.25 mg l-1 of a common biofertilizer (mustard oil cake). The 96hr-LC50 dose of mustard oil cake of 5065.0  mg l-1 showed that it was slightly toxic (500-5000 mg l-1) or virtually non-toxic (5000-15000  mg l-1) nature to this fish with a safe level estimate of 101.30 mg l-1.  It was found that the weight, length and breadth of the fish showed a lower increase in treated fish when compared to control ones.  Better results were obtained from the fish under long-term treatment compared to short-term experiments. The long-term experimental fish value of the exponent of the length-weight relationship of 1.398 suggests negative allometric growth. The condition factor ‘K’ for the experimental fish was above 1.0 (1.64-1.82) indicating the relative condition of the experimental fish. The decline in the growth of fish in biofertilizer-treated conditions is due to the presence of anti-nutritional factors of biofertilizer. The observation would help to formulate cost-effective fish food, assessment of optimal biofertilizer dose for the higher yield and computational biomass of the sample of this fish.