The ichthyofauna of the upstream and downstream reaches of the KWA fall, Oban, Akamkpa L.G.A. cross River state, Nigeria

Abstract

A study of the fish status of Kwa falls water body was carried out for three months (August-October) and a total of 562 fish representing 12 species belonging to 11 genera from 10 families and 6 orders were sampled. The family Clariidae was represented by Clarias gariepinus, Cichlidae by 2 species: Oreochromis niloticus and Tilapia zillii, Mockokidae by Synodontis omias and Schilbeidae by Schilbe uranoscopus. Claroteidae by 2 species: Chrysichthys nigrodigitatus and Chrysichthys longipinnis, Mugilidae by Mugil falcipinnis. The rest includes Paralichthyidae (Citharichthys stamflii), Characinidae (Sarcodaces odoe), Eleotridae (Eleotris vittata) and the Cyprinidae (Barilius niloticus). Siluriformes and Perciformes were the most abundant orders accounting for 72.2% and 14.8% of the total landings respectively while the species Chrysichthys nigrodigitatus (313), C. longipinnis (72) and Oreochromis niloticus (56) dominated the overall catch constituting 87.5%. Monthly differentiation in the diversity indices revealed higher values for the month of October than the month of August and September. The Shannon-wiener index (H’) obtained were within the range of 0.75 to 1.74 and showed significant difference between reaches, with downstream reaches having higher diversity throughout the sampling period. Equitability values (E) were generally low in all the reaches sampled. The spatial and seasonal differences were significant at p