MORPHOMETRIC AND MERISTIC VARIATION OF CICHLIDS IN ZOBE RESERVOIR, KATSINA STATE, NIGERIA

Abstract

Tilapia are diverse species with high similarities within and among genera, hence, they can easily be misidentified using a
few body features. Wrong identification of fish species might lead to wrong estimation and faulty management strategies.
Morphomeristic methods are ancient methods of fish taxonomy and are still in use globally. This study investigates the similarities and differences among the Cichlids species in Zobe reservoir using a total of 100 fish samples belonging to the Cichlidae family and identified using field guide. Out of the fish collected, 72 were used for the morphomeristic analysis (18 per species identified) using 24 morphometric characteristics and 6 meristic counts. Morphometric and meristic data were normalized and analyzed using Principal Component Analysis and Canonical Discriminant Analysis with PAST Software.
Four species, Oreochromis niloticus, Oreochromis mossambicus, Coptodon zilli and Sarotherodon galilaeus belonging to three genera were identified in the study area. The Principal Component Analysis (PCA) resolved 3 components which accounted for 83.32% of the total between species variation but still showed high level of overlaps among the species. The overlap was for O niloticus, O. mossambicus and S. galilaeus. 1 and 2 Canonical Discriminant Analysis (CDA) accounts for 92.34 % and 95.0% in morphometric and meristic counts of among-group total variability respectively. The Discriminant analysis for morphometric data showed partial speciation and overlaps between the species, while meristic counts revealed complete speciation in gill rakers, lateral line scales, number of dorsal and anal rays. Morphomeristic identification of cichlids should be based on meristic counts especially gill rakers, lateral line scale, dorsal and anal rays. Therefore, a field guide with meristic counts should be employed always.