Genetic barcoding of flatfishes reveals diverse species distribution patterns along the Tanzanian coast

Abstract

Flatfishes are important components of benthic communities and support small-scale fisheries that sustain livelihoods in the southwestern Indian Ocean. However, limited data on their diversity and distribution hinder effective management and conservation, especially under growing threats from destructive fishing and climate change. To address this, 134 flatfish specimens from the Tanzanian coast were analyzed. Specimens were initially identified through morphological examination and their species identities were confirmed using DNA barcoding. Partial fragments of the cytochrome c oxidase subunit I gene were sequenced and the resulting sequences matched against the Barcode of Life Data System and GenBank databases. Nine flatfish species across five families were recorded: Bothus pantherinus, Cynoglossus acaudatus, Cynoglossus attenuatus, Cynoglossus durbanensis, Engyprosopon grandisquama, Paraplagusia bilineata, Pardachirus marmoratus, Psettodes erumei, and Pseudorhombus arsius. Species composition and distribution varied by location, with P. marmoratus being the dominant species and P. erumei showing the widest distribution. Engyprosopon grandisquama and P. bilineata were rare and restricted to specific habitats, suggesting their current IUCN Least Concern status should be reassessed. One Bothus sp could not be identified using existing reference databases. These findings highlight the need to expand genetic databases, strengthen monitoring, and protect key habitats to support flatfish conservation in the region.