Invasive Asian swamp eel threatens Everglades food web, outpacing Burmese python impact

The Asian swamp eel (Monopterus albus), an air-breathing freshwater fish native to East and Southeast Asia, has been present in Florida since 1997 and is now entrenched in Everglades habitats, including Taylor Slough and the Arthur R. Marshall Loxahatchee National Wildlife Refuge, where it was confirmed in 2025. Research led by Nathan Dorn of Florida International University and colleagues documented dramatic reductions—up to 99%—in native crayfish and small-bodied fish after eel colonization, with overall fish and decapod richness falling about 25% and biomass dropping 68%, severely affecting prey for wading birds.

A 2026 Freshwater Biology study found that eel density best predicts amphibian declines, notably the loss of southern leopard frogs, while tree frogs are less impacted. The eel’s ability to breathe air and burrow into drying mud lets it survive low-water periods, making control virtually impossible. Attempts to devise effective traps have so far been unsuccessful, prompting calls for new management strategies. While Burmese pythons remain a high-profile invasive predator, scientists caution that the eel’s impact on the lower food web could be even more detrimental, a view echoed by the U.S. Fish and Wildlife Service, which lists the species as High Risk.