Sex ratio and fecundity of Chrysichthys nigrodigitatus (Family - Claroteidae) from Asejire Lake, Nigeria
Keywords:Chrysichthys nigrodigitatus, body weight, standard length, condition factor, goats
Sex ratio and fecundity of Chrysichthys nigrodigitatus from Asejire Lake were examined. The length-weight relationship showed that weight was curvilinearly related to standard length. The logarithm transformation of weight against standard length gave a straight-line graph represented by the following equation:
Log W = -0.66 + 2.13 Log sl
r2= 0.854; (p<0.001) n = 209
Males were generally more with a male : female ratio of 1:0.18. The average fish weight was 88.97g (16.28 cm standard length). Sexual maturity was attained at an average size of 45.0g (14.0 cm standard length). Relative fecundity was dependent on body weight and standard length (P< 0.05 and P < 0.01 respectively). Chrysichthys nigrodigitatus expended between 0.75% - 27.30% of body weight in egg production. The condition factor values showed that a female specimen of equal length with a male specimen is heavier. Six gonad maturity stages were identified, ovary and gonad weights increased with stage of maturity.