Hydrocynus goliath

Hydrocynus goliath, commonly known as the goliath tigerfish, giant tigerfish, or mbenga, is a large species of African predatory freshwater fish in the family Alestidae. It is native to the Congo River Basin and Lake Tanganyika in Africa.

Distribution

The goliath tigerfish is one of five recognized African species of the Hydrocynus genus and is found in the Congo River Basin (including Lualaba River and Lake Upemba), and Lake Tanganyika. The type locality is the city of Mbandaka in the Main Congo, where it was discovered in 1898 by French explorer Boulenger. They are typically found in highly oxygenated fast-flowing waters such as those found in deep river channels and open lakes, making them strong swimmers able to capture prey even in turbulent waters.

A 2011 study which reconstructs the phylogenetic history of genus Hydrocynus using comparisons of a protein-coding gene called cytochrome b, revealed several mtDNA clades in this region, suggesting a higher tigerfish species richness than traditionally recognized. The study's analyses indicate that populations of H. goliath may have been prevented from upstream dispersal in the geologic past by knickpoints, or sharp changes in the channel bed slope, in the Luvua river. This prevention of upstream dispersal would restrict H. goliath to the Congo River Basin as reflected in the modern range of the species. Four additional species (H. vittatus and three unknown species) appear to be present in this Basin, while two (H. vittatus and an unknown species) appear to be present in Lake Tanganyika.

Based on the study's sequence comparisons, H. goliath possesses low nucleotide diversity, suggesting that existing populations originate from a historically small effective population which underwent rapid population growth at some point in the past.