Food, Feeding and Reproductive Biology of Clarias anguillaris (Linnaeus, 1758) in Orogodo River, Delta State, Nigeria

Abstract

Along with two other species of Clarias (C. gariepinus and C. macromystax) in Orogodo river, C. anguillaris form an important component in the delicacy of inhabitants of the area where they are harvested in large quantity by artisanal fishermen, yet information on its biology/ecology in Orogodo river are lacking. Food habits and reproductive biology of Clarias anguillaris in Orogodo river, Delta State, Nigeria was investigated between January, 2023 and December, 2024. Frequency of occurrence, numerical and point methods were used to investigate food habits from three hundred and twenty four (324) stomach samples of this species. Sexes of fish were determined and sex ratio was estimated for each month. Fecundity of the species was estimated from seventy four (74) ripe ovaries by direct count and gravimetric method. Relationship between fecundity and fish length and weight was estimated using regression and correlation analysis, while Gonadosomatic index (GSI) was calculated using one hundred and thirty eight (138) samples of females with ripe ovaries. Food items in the stomach were majorly detritus, chironomus larvae and pupae, mud and ostracoda. Feeding intensity of the species did not follow any distinct seasonal pattern with highest percentage (7.0%) gained recorded in November and December 2024 while the least (3.4%) was in February 2023. Percentage of empty stomach also showed irregular fluctuation during the study period. Diel variation in feeding intensity indicated that the species fed more at night than day time. Fecundity of the species ranged between 285 and 1250 eggs. The species spawned mostly during the rainy months (April to October) which also coincided with the period of highest GSI values. Fecundity was positively correlated to both body weight (r= 0.6430) and standard length (r= 0.5290). The wide spectrum of food items fed upon by the species here reflects the availability of food in the habitat and an adaptation to intra and interspecific competition while the relatively low fecundity recorded reflects the general well-being of the species in the habitat. The euryphagous feeding habit of this species and the multiple spawning patterns are findings that would ultimately be of relevance to future researchers, conservationist and fish culturist interested in the exploitation and management of fish resources in the wild.