Vol. 14 No. 65-73 (2023): SOME ASPECTS OF BIOLOGY OF Clarias gariepinus IN SHIRORO RESERVOIR, NIGER STATE, NIGERIA

Biology of fish is useful in the stock assessment of fish in the water body, particularly in the conduct of population analysis of fish, where information on the age of fish is crucial. Some aspects of biology of Clarias gariepinus in Shiroro Reservoir, Niger State, Nigeria was investigated. Sixty – two (62) samples of Clarias gariepinus were collected and used for this study. Twelve (12) morphometric parameters that included weight, pre – dorsal length, head length, standard length, dorsal length, total length, eye diameter, pectoral fin length, body depth, pelvic fin length, anal fin length and caudal peduncle depth were measured with both higher and lower variations. Positive relationship was recorded between head length with pre – dorsal length, standard length with head length, total length with head length and standard length, anal fin length with head length, standard length and total length. Class size of 5.00 - 9.90cm was highest overall, where majority of male (40.32%) and female (33.87%) both also fell within the class 5.00 – 9.900cm. Monthly class size showed variation with 5.00 – 9.90cm recorded throughout the month. Sex ratio of 1:1.07 showed more population of female to male in the reservoir, which did not differ from 1:1 for a balance population. Monthly sex ratio showed more males in April and May, more females in June and balanced population in July. Morphometric parameters with strong positive relationship should be used to describe or differentiate C. gariepinus from other species of fish, catching of C. gariepinus at that period in the reservoir need to be discouraged or removal of small sizes should be stopped, other aspects of biology of Clarias gariepinus such as food composition, fecundity, growth and amongst others need to be studied.