Fish Species Composition, Diversity and Community Structure of Ibikpe Creek, a Tropical Freshwater System in the Niger Delta, Nigeria

Abstract

The ichthyofauna of Ibikpe Creek, a previously unsurveyed tropical freshwater system in Uruan Local Government Area, Akwa Ibom State, Niger Delta, Nigeria, was investigated monthly from June to December 2025 at three sampling stations. Sampling was conducted using unbaited gill nets (mesh sizes of 25–75 mm and approximately 30 m in length) set overnight at vegetated marginal zones by experienced local artisanal fishers. Specimens were identified using regional keys (Idodo-Umeh, 2003; Olaosebikan & Raji, 1998). A total of 60 fish specimens belonging to 16 species, 13 genera and 7 families were recorded. Cichlidae was the most speciose family (8 species; 26 specimens, 43.5% of total abundance), followed by Alestidae (3 species; 6.5%); Anabantidae, Notopteridae, Polypteridae, Cyprinidae and Hepsetidae were each represented by a single species. Ctenopoma kingsleyae was the single most abundant species (20 specimens; 33.3% frequency of occurrence), while seven species were each represented by a single specimen (1.7%). Monthly abundance was highest in July and August (12 specimens each) and lowest in November and December (5 each); the four highest-abundance months fell within or immediately adjacent to the wet season. Species diversity, the Shannon-Wiener index and Margalef’s richness index were highest in June (7 species; H′ = 1.846; d = 2.502). These findings provide the first documented species checklist and community-structure baseline for Ibikpe Creek, indicating a species-poor, wet-season-favoured assemblage dominated numerically by a single air-breathing anabantid, and establish a reference point for future monitoring and conservation planning.