Snakehead fish are predatory freshwater fish known for their distinctive elongated bodies and flattened heads, giving them a snake-like appearance. Originating from parts of Asia and Africa, these fish are well-adapted to various freshwater environments. They are also known for their aggressive hunting behaviors and unusual capabilities outside of water.
Terrestrial Movement Explained
Snakehead fish can move on land, though their movement is more of a wriggle or slither than a walk. They achieve this propulsion by combining strong body undulations with movements of their fins and head. This method allows them to navigate across various terrains, including muddy surfaces and vegetation.
They move overland to escape drying or oxygen-depleted water bodies, seeking new aquatic habitats. They can also move to colonize new areas, hunt for prey in shallow or isolated spots, or expand their territory. While adults might be more lethargic on land, younger snakeheads have been observed migrating over short distances, sometimes up to a quarter mile, to find new water sources.
Survival Out of Water
Snakehead fish survive out of water for extended periods due to several physiological adaptations. They possess a unique respiratory system that includes a suprabranchial organ, a primitive lung-like structure located above their gills. This organ allows them to breathe atmospheric oxygen by gulping air from the surface, supplementing the oxygen absorbed through their gills. This adaptation means they can thrive in stagnant or low-oxygen waters where other fish might not survive.
To retain moisture and prevent desiccation, snakeheads secrete a protective layer of mucus over their skin. This mucus, along with their naturally slimy bodies, helps keep them moist. Depending on the species and environmental conditions, snakeheads can survive out of water for several hours to up to four days, provided their skin remains moist.
Ecological Impact and Management
The unique terrestrial abilities of snakehead fish contribute to their status as an invasive species in many non-native regions, such as the United States. Their capacity to move between water bodies facilitates their spread, making containment challenging. The Northern Snakehead, native to East Asia, has established breeding populations in several U.S. states, often introduced through unauthorized releases from live fish markets or aquariums.
As voracious predators, snakeheads pose a threat to native ecosystems. They compete with native species for food and habitat, consuming a wide range of prey including other fish, crustaceans, amphibians, and even small birds and mammals. Their predatory behavior can disrupt food webs and lead to declines in native fish populations.
To manage their spread, federal law categorizes the Northern Snakehead as an “injurious” species, making it illegal to import, export, sell, or transport live specimens across state lines. If encountered, the public is advised not to release a live snakehead back into the water. Instead, anglers are encouraged to kill any snakehead caught immediately by methods such as removing its head, gill arches, or internal organs, and then report the sighting to local or state natural resource authorities.