Dramatic Decline in Snakehead Fish Population at Sun Moon Lake: Officials Investigate Potential Causes

Once a major invasive threat, the snakehead fish population at Sun Moon Lake has plummeted, leading authorities to explore reasons ranging from successful control measures to competition from a new invasive species.

The invasive snakehead fish, once a significant threat to the ecological balance and native fish species of Sun Moon Lake in Taiwan, has seen a dramatic decrease in its population. Since 2020, the Nantou County Government has been implementing electric fishing methods to remove juvenile snakehead fish. In peak years, over 35,000 individuals were removed annually. However, this year, only approximately 900 snakehead fish have been removed so far.

County officials are analyzing potential reasons for this sharp decline. One possibility is the effectiveness of the ongoing control efforts. Another hypothesis being considered is the impact of a newly emerging invasive species, the "Crown Cichlid" (皇冠三間), which may be outcompeting the snakehead fish for resources and habitat, thereby reducing their population.

Snakehead fish, also known as Channidae, are native to Southeast Asian countries including Sumatra, Thailand, Malaysia, India, Vietnam, Laos, and Myanmar. They are predatory fish, characterized by their large size and aggressive feeding habits. They typically nest and mate between May and June, with their eggs hatching and young fish emerging in the summer. The juvenile fish form "fish balls" under the protection of adult snakehead fish to hunt. As invasive species in Taiwan, they lack natural predators, posing a severe threat to the survival of native fish populations.