SNAKEHEADS: Channoidei

PHYSICAL CHARACTERISTICS

Snakeheads have a long tube-shaped body and flat head covered in large, shield-like scales. They have long soft dorsal and anal fins, a large mouth with large teeth on both upper and lower jaws, smooth or rough body scales, and an air-breathing organ in the head. The dorsal (DOOR-suhl) fin is the one along the midline of the back. The anal (AY-nuhl) fin is the one along the midline of the belly. Many snakeheads have large spots resembling eyes on the body and on the tail fin, up-and-down bands on the pectoral fins, and small spots on the body. The pectoral (PECKter-uhl) fins correspond to the front legs of four-footed animals.

GEOGRAPHIC RANGE

Snakeheads are native to Asia and Africa and have been introduced in the United States, Russia, and the islands of the South Pacific.

HABITAT

Most snakeheads live in still or slow-running waters, usually hiding under plants, rocks, and sunken trees. Some large species live in large rivers, swamps, ponds, and reservoirs. Most small species live in mountain streams. Many snakeheads can live in polluted water.

DIET

Adult snakeheads eat almost any animal smaller than their mouths, such as insects, fishes, frogs, tadpoles, lizards, geckos, mice, rats, and ducks.

BEHAVIOR AND REPRODUCTION

All but one species of snakeheads are active during the day and hunt by ambush. Adults hunt alone, but young snakeheads hunt in schools. Snakeheads sometimes jump up from the water surface to grasp their prey. Snakeheads need to break the water surface once in a while to exchange the air in their breathing organ. These fishes drown if they cannot get to the surface to breathe. Some species of snakeheads can live out of water for several days if their bodies are wet. They can travel on land during the rainy season by using their bodies, pectoral fins, and tail fins.

Scientists know little about the reproduction of snakeheads. These fishes probably have only one mate and take care of their eggs and young. Many snakeheads clear plants and then build a simple circular nest at the water surface. The male encircles the female, squeezes out her eggs, and fertilizes, or places sperm on, them. The eggs float upward into the nest, which the parents guard. After hatching, the young are cared for by either parent, depending on species. In two species the male keeps the fertilized eggs and later the young in his mouth for a few days.

SNAKEHEADS AND PEOPLE

Most snakeheads are important food fishes in Southeast Asia and China, and the meat is considered delicious. Some medium-to-large species are farmed. Larger snakeheads are popular game fishes in Asia.

SNAKEHEAD INVASION

Scientists worry about a North American invasion of snakeheads because the fish eat up the food needed by other fishes and then eat the other fishes. Snakeheads have been a problem in Maryland, and on October 14, 2004, a snakehead was caught for the first time in Lake Michigan.

CONSERVATION STATUS

Snakeheads are not threatened or endangered.

STRIPED SNAKEHEAD (Channa striata): SPECIES ACCOUNT

Physical characteristics: Striped snakeheads are about 24 inches (60 centimeters) long. There are no scales on the underside of the jaw. The scales on the body are moderately large. The fish are dark brown on the back, but the color extends into irregular blackish bands on the sides. There are no bands or spots on the pectoral fins. Young striped snakeheads have a black spot at the end of the dorsal fin.

Geographic range: Striped snakeheads are native to Southeast Asia.

Habitat: Striped snakeheads live in still to slow-running waters with a muddy bottom, such as ponds, swamps, and ditches.

Diet: Striped snakeheads eat smaller fishes, frogs, prawns, and worms.

Behavior and reproduction: Striped snakeheads can survive in the bottom mud of lakes, swamps, and canals that have dried up. They can move over land during the rainy season. Male and female striped snakeheads use their mouths and tails to clear away dense plants to make a doughnut-shaped floating nest about 12 inches (30 centimeters) in diameter, into which they place the eggs. The hatching period lasts about three days, during which the male guards the nest. After hatching, the young, still protected by the male, move in a dense school to look for food.

Striped snakeheads and people: Striped snakeheads are an important food fish.

Conservation status: Striped snakeheads are not threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Dolin, Eric Jay. Snakehead: A Fish out of Water. Washington, DC: Smithsonian Books, 2003.

Web sites:

Babin, Don. "Scientists Relieved They Don't Find Northern Snakehead in Chicago Harbor." Great Lakes Directory.http://www.greatlakesdirectory.org/il/101904_great_lakes.htm (accessed on November 8, 2004).

"Snakeheads: The Newest Aquatic Invader." U.S. Fish and Wildlife Service. http://contaminants.fws.gov/OtherDocuments/snakeheaddistill.pdf (accessed on November 8, 2004).