Length-weight relationship and condition factor of Chrysichthys nigrodigitatus from Lake Akata, Benue State, Nigeria

Abstract

The fishery of Lake Akata is well known but little has been studied about it. Result of an aspect of the biology of Chrysichthys nigrodigitatus is here presented. Length-weight relationship and changes in the condition factor of C. nigrodigitatus were analysed from samples collected between May 2008-April 2009, in Lake Akata an ox-bow Lake of River Katsina-Ala, a tributary of River Benue. The mean weight and standard lengths of (n = 920) unsexed individuals of C. nigrodigitatus, were 211.7g±6.4 and 20.66cm±0.30. The growth pattern of both male and female C. nigrodigitatus was determined to be approximately isometric. The Length-Weight relationship equation for male and female C. nigrodigitatus were LogW= –1.8757 + 3.0340 LogL and LogW= –1.5225 + 2.8011 LogL, respectively. The combined length weight relationship for both sexes was LogW = –1.7515 + 2.9569 Log L. The overall condition factor was 1.62 ±0.01 for males and females combined but individually, female C. nigrodigitatus were in better condition (1.73±0.02) compared to the males (1.50±0.02). The variation in physiological, condition is associated with sex ratio and reproductive activity. C. nigrodigitatus in Lake Akata exhibits isometric growth with differences in condition of males and females but seasonal differences in condition was not observed.