Morphological and molecular evidence reveal the Sarotherodon melanotheron invasion off Taiwan, East Asia

The blackchin tilapia, Sarotherodon melanotheron Rüppell, 1852, is a highly euryhaline cichlid native to West and Central Africa. Due to its broad salinity tolerance and rapid reproduction, it has become a high-risk invasive species in brackish and coastal ecosystems worldwide. This study reports the first and northernmost confirmed record of wild blackchin tilapia population in East Asia, based on 13 specimens collected from coastal waters of Kaohsiung City, Southern Taiwan. Morphological and meristic data, together with cytochrome c oxidase subunit I (COI) gene sequencing, confirmed species identity and consistency with native and invasive populations elsewhere. The occurrence of mature individuals and a substantial wild population confirms the establishment of invasion population in Taiwanese coastal environment. Given its wide salinity tolerance and omnivorous diet, this species poses potential ecological and economic threats to native ecosystems and aquaculture. This finding also represents the northernmost record of blackchin tilapia in the western Pacific.