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Length-weight Relationship and Condition factor of Chrysichythys nigrodigitatus and Schilbe mystus in Erelu Lake, Oyo State, Nigeria

Kareem OK, Olanrewaju AN and Orisasona O

The study on length-weight relationship and condition factor of Chrysichythys nigrodigitatus and Schilbe mystus from Erelu Lake, Oyo was conducted monthly for Twenty-one months (July, 2013-March, 2015). A total of One thousand one hundred and seventy-nine (1179) fish samples composed of Six hundred and twenty-eight (628) C. nigrodigitatus and Five hundred and fifty-one (551) S. mystus were collected using gill nets. The specimens were preserved in ice-packed box and taken to laboratory for length - weight measurement. The length-weight relationship was estimated using the linear regression model W=aLb and condition factor, (k) determined using the equation K= 100.W/L3. The result revealed preponderance of females (301 and 382) over males (250 and 246) for S. mystus and C. nigrodigitatus respectively in the population. Negative allometric growth was recorded for both species and sexes. The values of (b) ranged from 1.76 to 2.56 for C. nigrodigitatus and 2.20 to 2.95 for S. mystus. Also, the condition factor were varied between 0.199 and 2.053 for C. nigrodigitatus and 0.172 -2.417 for S. mystus but female C. nigrodigitatus and S. mystus have higher k value than their male counterpart indicating better state of well-being when compared to the males. A further investigation on the bionomics of fishes in this lake is advocated to substantiate the results of this study.