Some Aspects of the Biology of the Catfish in Chekoilel River.

Abstract

The local catfish, Clarias from Chepkoilel river/swamp were studied from November, 2008 and March, 2009. This study reports their length-weight relationship, body condition, food and food habits, fecundity, sex ratio and reproductive status. The samples were caught by hook-and-line, seine net and gill nets from Marura Bridge, Kuinet Bridge and Moi University Chepkoilel Campus Fish Farm (M.U.C.C.F.F.) reservoir. The length-weight relationship was calculated for each sex separately. The regression equation for males (n = 39) was Log.W = 0.033L2.421 and for females LogW = 0.056L2.235. The catfish showed a negative allometric growth. The mean condition factor for females was 5.69 and 3.42 for males which were significantly different (t-test, df = 1, p<0.05). The mean size of females (n = 47) was found as 14.41 (± 0.40 S.E.) ranging from 10.10-20.70cm TL, while males (n = 39) had a mean size of 20.93 (± 0.84 S. E.) and ranged from 11.60-32.10cm TL. A one way ANOVA showed that males were significantly longer than females. The mean body weight for females was 23.17 (± 1.60 S.E.) ranging from 8.85-58.41g while males had a mean body weight of 60.16 (± 6.15 S. E.) and ranged from 10.04-142.65g. A one way ANOVA showed that males were significantly heavier than females. The sex ratio of 1:1.20 in favour of females was not significantly different from expected ratio 0f 1:1 (χ2 = 0.744, df = 1, p = 0.388, n = 86). The minimum size at first sexual maturity was found to be 15-20cm TL for females and 17-19cm TL for males. Fish of both sexes occurred in the maturity stages II-VI, while only one male occurred in stage I; ovaries in stage VI had mature unshed eggs. Examination of the stomach contents revealed that the catfish were largely indiscriminate feeders, feeding on a variety of organisms including other fish species.