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A population of non-native aggressive, air-breathing fish known as the goldline snakehead (formerly known as “bullseye snakehead”) was documented for the first time in the Gulf Coast region, the U.S. Geological Survey reports. The fish were discovered in a freshwater pond in Manatee County, Florida, about 250-km from the only other known population of this species in the United States, which has existed in Broward County, Florida, since about 2000.

Native to Asia, snakeheads have been introduced to the wild worldwide due to their popularity in the live-food and ornamental fish trades and even sport fishing. However, the predatory fish is able to withstand diverse environmental conditions, including drought, and has the potential to cause damage to native ecosystems.

Upon discovery of the non-native species in Manatee County, nets, electrofishing, and a chemical known as rotenone were used to remove almost 400 snakeheads from the pond, with some of the specimens transported and catalogued in the ichthyological collection of the University of Florida’s Florida Museum of Natural History. Seven other non-native species, including walking catfish, Asian swamp eel, jewelfish, and brown hoplo, were also removed.

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Scientists compared physical features, such as the number of fin rays, and genetic make-up of both populations, which revealed them to be similar, suggesting the snakehead population found in the Manatee County pond was introduced from the Broward County population. However, because of the distance between the populations, the snakeheads in Manatee County are likely a result from human transport between sites rather than natural dispersal. 

The researchers also found that the genetic make-up of the Florida snakehead populations was nearly identical to snakeheads from a native population in Thailand, indicating the non-native fish likely originated in the southeast Asian country.

The report also provides observations of a rarely seen behavior of snakehead in the wild: terrestrial hunting. While snakeheads are known to move over land, their ability to feed while doing so emphasizes the fish’s potential negative impact on native species.

The snakehead population found in Broward County in 2000 has since expanded its range into Miami-Dade and Palm Beach counties via southern Florida’s extensive canal system.

Surveys in surrounding waters after the removal effort in Manatee County revealed no snakeheads had spread beyond the pond. However, further monitoring is needed to ensure the non-native fish have been eradicated.