Report on the incidences of skeletal anomalies in three fish species from Bonny tributary (Niger delta), Nigeria

Abstract

Three cases of skeletal anomalies in fishes Elops lacerta Valenciennes, 1847 (family Elopidae), Oreochromis niloticus (Linnaeus, 1758) (Cichlidae) and Arius latiscutatus Günther, 1864 (Ariidae) collected in the Elechi Creek, a tributary of the Bonny River (Niger delta) were reported for the first time in the present study. The anomalies are pugheadness, complete absence of pelvic fins and deformed dorsal, pectoral and pelvic fins. Three specimens of E. lacerta have shown the case of pugheadness but at different levels of severity. The specimen of O. niloticus showed a complete absence of the pelvic fins. Externally, the area where the bases of the pelvic fins should be found (underneath the pectoral fins) showed a normal scale covering (in scale form and size). Internally and by using radiography, no trace of the pelvic fins and the basipterygia were observed. The specimen of A. latiscutatus showed severe deformation of the finrays of the dorsal, pectoral and ventral fins. The spines of the pectoral and dorsal fins were also deformed. Pollution from Port Harcourt appears to be causing the skeletal deformities described.