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Photo credit: Robinet Tony - MNHN/CC BY-NC 3.0
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Species at a Glance
The blotched snakehead is a freshwater obligate air breather that possesses an air bladder that works like a primitive lung, allowing it to survive out of water in moist locations for several days. While other species of snakehead have been known to wriggle short distances over wet lands to new bodies of water, this behavior has not been documented for this species. These adaptations may give snakeheads a competitive edge in securing habitat and expanding their range.
Snakeheads have a long, torpedo-shaped body that can grow to a maximum size of 85 cm (33 in). The dorsal and anal fins are long and continuous, running along the top and bottom of the body and nearly reaching the caudal fin. As the name implies, the scaled head of the fish looks like a snake. The mouth is large with sharp teeth, and a truncate (not rounded) tail. Coloration is generally tan to black with irregular blotches or spots along the sides.
The native bowfin (Amia calva) is often mistaken for snakeheads. The bowfin is distinguished by a rounded tail, scaleless head, and an eyespot near the tail in males. The burbot (Lota lota) can be distinguished by its split dorsal fin and a single barbel on the lower jaw. The dorsal and anal fins of the bowfin and burbot are also short in comparison to snakeheads. The northern snakehead and blotched snakehead look very similar to each other, although the blotched snakehead generally has dark bar-like marks preceded by pale bar-like areas. The northern and blotched snakehead also differ in the number of scales in the lateral line, as well as rays in the dorsal and anal fins.
Most snakeheads can be found in streams and rivers. The blotched snakehead prefers stagnant shallow ponds, swamps, and slow streams with mud or vegetated substrate. It can tolerate low oxygen conditions, and survive in waters that are covered in ice.
The sale of live snakehead in pet shops and live food-fish markets in the United States may have contributed to their introduction. When they grow too big for aquarium tanks, uninformed pet owners may release them into the wild. In addition, they have also been released as part of religious or cultural practices. In 2002, the import and interstate transport of the northern snakehead was banned without a permit from the U.S. Fish and Wildlife Service.
The blotched snakehead is native to Asia. While not yet confirmed as established on the mainland, has been established in Hawaii since the 1800s, and single individuals have been collected in North Carolina and Massachusetts.
Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.
While impacts of the blotched snakehead remain unknown, this species has the potential to compete directly with native species for food and habitat. It may also prey directly on native fish, crustaceans, frogs, small reptiles, and sometimes even small birds and mammals, although adults feed almost exclusively on fish, and such impacts have yet to be documented. Similarly, no adverse impacts on managed populations of introduced sport fishes (e.g., largemouth bass) have been documented to date.
Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).