International Journal of Fisheries and Aquaculture Vol. 3 (12), pp. 225-230, November 2011 Available online at http://www.academicjournals.org/IJFA DOI: 10.5897/IJFA11.072 ISSN 2006-9839 ©2011 Academic Journals Full Length Research Paper Parasites of landed fish from Great Kwa River, Calabar, Cross River State, Nigeria Ekanem A. P. 1 *, Eyo V. O. 1 and Sampson A. F. 2 1 Department of Fisheries and Aquaculture, University of Calabar, Nigeria. 2 Department of Marine Biology, University of Calabar, Nigeria. Accepted 21 October, 2011 Parasites of landed fish from the Great Kwa River, Calabar, Cross River State, Nigeria were studied. Parasitological examination of 180 fish samples belonging to 9 taxa from the River showed 50% incidence for Chrysicthys nigrodigitatus, 16.67% for Heterotis noloticus, Clarias gariepinus and Tilapia galileaus respectively and 0% for Hepsetus odoe, Arius gigas, Momyrus rume, Ethmalosa fimbriata and Cynoglossus senegalensis. Parasite infestations were found in the stomach and intestine, and no parasites were found on the fins, skin and gills. Nematodes, cestodes and protozoan were found in decreasing order of abundance. Diphyllobothrium sp. was found in the intestine of C. nigrodigitatus; Camallanus sp. was found in the intestine of H. niloticus and T. galileaus while protozoan cysts were found in the intestine of C. garipinus. Parasites were more prevalent in the fish of 30 to 39.9 cm total length size range. The study determined that in the Great Kwa River the preferred organs of parasites were the intestines and stomach. Key words: Parasites, landed fish, Great Kwa River. INTRODUCTION Fish are important source of income and food in Nigeria and other countries in the sub-Saharan Africa, where some 35 million people depend wholly or partly on the fisheries sector for their livelihood (FAO, 1996). In Nigeria, consumption and demand for fish protein is increasing due to its affordability. Parasites play an important role in the ecology of aquatic ecosystems as well as in the aqua - and mariculture industries. Apparently, the origin of most diseases in mariculture is likely to be the wild-caught fingerlings or juvenile fish (Martens and Moens, 1995). In Nigeria, the vast majority of the supply of fish comes from river systems where fish are landed at fishing jetties and purchased for distribution by large and small scale fish dealers. *Corresponding author. E-mail: albertekanem@yahoo.com. Parasites of fish are a concern since they often produce a weakening of the host`s immune system thereby increasing their susceptibility to secondary infections, resulting in the nutritive devaluation of fish and subsequent economic losses (Onyedineke et al., 2010). In fish culture systems, parasites have often been implicated as the main cause of economic losses (Khalil and Polling, 1997) and parasite species found to cause none or limited pathological damage in wild fish may, under conditions of mariculture, become pathogenic (Diamant and Paperna, 1986; Overstreet, 1978). The possibility of disease transmittal from fish to humans through fish consumption is a public health concern (Ibiwoye et al., 2006). Kabata (1985) reported that Clinostomum (Acanthocephalans) when ingested with poorly cooked fish is capable of producing laryngoharyngitis which is an unpleasant inflammatory condition. Parasite infection of the body cavity and the