Studies on Characterization of Members of Two Fish Genera, Hydrocynus and Alestes, From the White Nile and Lake Nubia

Abstract

Members from species of two genera of the Nile fishes Hydrocynus and Alestes were collected from Lake Nubia at Wadi Halfa and from Jebel Aulia at the White Nile. Collection was done during the period from May 2001 to March 2005. Eight species were studied for morphometric measurements and ratios, cytogenetic patterns and protein polymorphism. Morphometric measurements taken included the total length (L), standard length (SL), depth (D), interorbital width (IOW), eye diameter (ED), peduncle length (PL) and peduncle depth (PD). Measurements and ratios revealed significant differences between members of the species collected at the two freshwater systems. The cytogenetic study revealed a chromosome complement of 2n= 56 for Hydrocynus species members and 2n= 42 for Alestes species members. Chromosomes were found to vary in structure within the complement where, metacentric, telocentric and acrocentric chromosomes were recorded. Chromosomal fusions and polyploidy were also recorded, and suggestion of recent chromosomal rearrangements in members from the two geographic locations is proposed. Profiles of total protein were done using electrophoresis; genetic variation is detected at this level between taxa of the two water systems. The electrophoretically separated soluble protein bands showed presence of polymorphic alleles in members of the same species caught from Lake Nubia and the White Nile