Microalgae, Zooplankton and Macroinvertebrate Food Components of Oreochromis Niloticus (Piscis: Cichlidae) in Liberty Reservoir, Jos, Nigeria

Abstract

The food of Oreochromis niloticus (Linnaeus, 1758) in Liberty Reservoir, Jos, Nigeria was studied based on the characterization of microalgae, zooplankton and macroinvertebrates present in the stomach of the cichlid. A total of 55 adult O. niloticus (Total length range 82-259 mm) were procured on the 10th of October 2014 from one of the fishermen who set fish traps in the reservoir and taken to the laboratory for stomach contents analysis. The percent frequency of occurrence and the numerical percentage methods were used to analyse the stomach contents of the fish samples. Only 56.36% of the fish had food in their stomach. A total of 98 taxa of prey items (made up of 17 genera of cyanobacteria, 27 genera of diatoms, 25 genera of chlorophytes, 15 genera of charophytes, two genera each of dinoflagellates and euglenophytes, one genus each of cryptophytes, heterokontophytes, chrysophytes and rhodophytes, and three zooplankton and two macroinvertebrate taxa) were found in the examined stomachs. Microalgae, primarily diatoms, constituted 99% of the diet with zooplankton and macroinvertebrates making up the residual 1%, showing O. niloticus in the Liberty Reservoir to be predominantly algivorous.