Comparative Ecology Of The African Bony Tongue Fish Heterotis Niloticus And The Catfish, Clarias Gariepinus In The Lower Oluwa River And Adjacent Floodplains

Abstract

The ecology of sympatric African bony tongue fish, Heterotis niloticus and the catfish, Clarias gariepinus were compared during the dry and rainy conditions in the lower Oluwa River and its adjacent floodplains. Both species are common economic fish in Nigeria. There was no significant difference in the mean sizes of H. niloticus and C.gariepinus from the samples collected during the rainy season and the dry season.
The river channels had the least number of the sampled species for both fish under study. Approximately 65% of the H. niloticus that were collected inhabited the Mahin floodplains while 74% of C. gariepinus were found in the same habitat. During the rainy season, most of the Heterotis caught were juveniles in the middle floodplains while juveniles of Clarias were caught in the upper floodplains. Phytoplankton accounted for over 62.53% of the total stomach contents of H.niloticus using the frequency of occurrence method, while fish parts constituted the highest percentage of components of C.gariepinus (16.62%). By volumetric method, plant materials formed the bulk of the 29.55% of food items observed in H.niloticus while fish parts also formed the highest portion of the diets (25.56%) in C.gariepinus. Fish population of both species were high in all the locations of the study area, however analysis of the preponderance of male to female during the two seasons of the year shows that there were more females to males during the rainy season for both species.


Key words: ecology, Heterotis niloticus, Clarias gariepinus, Oluwa River, floodplains

Ife Journal of Science Vol. 7(1) 2005: 15-20