Studies on the relative condition (K) in Clarias batrachus (Linn.) an endemic catfish of Assam from the Brahmaputra river system

Abstract

The results of a study of lengthwise and agewise relative condition (Kn) in Clarias batrachus (Linn.) collected from the swamp of the Brahmaputra river system are presented. The Kn values exhibit seasonal variations in close association with the gonadial development and feeding intensity of the fish. Fluctuations in K value in relation to various size, lengths and months are observed in both s~xes. The troughs formed by the low value of K on different size lengths in the curve of the relative condition factor almost n corresponds to the length at first maturity and subsequent spawning in later years. The proximate value of Kn observed in the curve of relative condition in relation to various months distinctly corresponds to the feeding intensity of the fish. The male fishes depict a comparatively better relative condition than females as indicated by K valUEls during spawning period (May-August) which is attributed to Ie sse: gonadial mass in them. However, females showed more or less a higher Kn values during prespawning and postspawning periods.