The first wild record of invasive redhead cichlid, Vieja melanura (Günther, 1862), in Hainan Island, China.
The redhead cichlid, Vieja melanura (Günther, 1862), is a freshwater and brackish water fish native to southern Mexico and Costa Rica. It was introduced into China as an ornamental fish species in the 1990s. During a comprehensive fish survey in Hainan Island conducted in April and August 2019, twenty redhead cichlid individuals, including two mature males, four mature females and fourteen juveniles, were captured at four sites in the Nandu River. This finding reveals that this species has successfully established feral populations in Hainan Island. This is the first report of the invasion success of redhead cichlid in Hainan Island, even in China. The redhead cichlid is very likely to compete with native species (e.g., Culter recurviceps) by occupying similar niches, thereby threatening the survival of native species and changing food webs, ecosystem structures and functions. Local governments and environmental protection organizations should carry out surveys to monitor the redhead cichlid invasion and implement interventions to prevent further spread. The escape of ornamental fishes to natural water bodies is an important contributor to elevated invasion risks, which should be paid attention to globally.