ABSTRACT
Fish are potential indicators of changing trends in aquatic environment because of the impact they have on distribution and abundance of other organisms in the water they inhabit. Information on the biology and ecology of fish species is vital for the realization of the full potential of fish for aquaculture purpose. This study was aimed at evaluating the species diversity, relative abundance, ecology and growth of fish species in Ogba River.
Fish specimens were caught by the assistance of hired fishermen using different gears (gill nets, hook and lines, bamboo traps, mesh net and basket traps). Fish sorting, identification and dissection were carried out in the laboratory using standard methods. Statistical analyses were done using general descriptive statistics, regression, t- test, chi-square, and unpaired t-test by the application of statistical package for social science (SPSS) and Microsoft word.
The result of ichthyodiversity evaluation showed that 637 fish specimens caught belong to 17species, 11 genera, and 8 families. The indices calculated for taxa richness showed that the highest number of species was found in Station 2. The cluster analysis indicated that there were similarities among species across the stations. The length – weight relationship of all the fish species showed that the fishes exhibited negative allometric growth with regression coefficient (b) ranging from 0.07 in Xenomystus nigri to 0.89 in Synodontis nigrit. The condition factor (K) varies among species and ranged from 0.83 in Erpetoichthy calabaricus to 4.06 in Chromidotilapia guentheri, suggesting they were in good condition expect in Erpetoichthy calabaricus. The food and feeding habit result showed the fish are mainly predatory, omnivorous and herbivorous feeders. The sex ratio between the number of male to female showed for fish species study shown there was no significant difference (p>0.05) from the excepted 1:1 ratio except in Parachanna obscura, Parachanna africana and Clarias pachynema (P< 0.05). Fisheries management requires proper understanding of the population dynamics of the fish stock which are major factors that influence the dynamics of a given population.
Key words: Species diversity, Ecology of fish species, Sex ratio, Length – weight relationships and condition factors.
