Snakehead Fish

The **snakeheads** are members of the freshwater perciform fish family **Channidae**, native to parts of Africa and Asia. These elongated, predatory fishare distinguished by their long dorsal fins, large mouths, and shiny teeth. They breathe air with gills, which allows them to migrate short distances over land. They have suprabranchial organs developing when they grow older, which is a primitive form of a labyrinth organ. The two extant genera are *Channa* in Asia and *Parachanna* in Africa, consisting of about 35 species. They are valuable as a food source and have become notorious as an intentionally released invasive species.

## Description

The various species of snakeheads differ greatly in size. Dwarf snakeheads, such as *Channa gachua*, grow to 25 cm (9.8 in) in length. Most other snakeheads reach between 30 and 90 cm (12 and 35 in). Five species (*C. argus*, *C. barca*, *C. marulius*, *C. micropeltes* and *C. striata*) can reach 1 m (3 ft 3 in) or more. Snakeheads are thrust-feeders that consume plankton, aquatic insects, and mollusks when small. As adults, they mostly feed on other fish (such as carp) or on frogs. In rare cases, small mammals such as rats are eaten.

## History

The Channidae are well represented in the fossil record and known from numerous specimens. Research indicates snakeheads likely originated in the south Himalayan region of the Indian Subcontinent (modern-day northern India and eastern Pakistan) at least 50 million years ago (Mya), during the Early Eocene epoch. Two of the earliest known species, *Eochanna chorlakkiensis*Roe 1991 and *Anchichanna kuldanensis* Murray & Thewissen, 2008, have both been found in the Middle Eocene of Pakistan. By 17 Mya, during the Early Miocene, Channidae had spread into western and central Eurasia, and by 8 Mya, during the late Tortonian, they could be found throughout Africa and East Asia. As Channidae are adapted to climates of high precipitation with mean temperatures of 20 °C (68 °F), their migrations into Europe and Asia correspond to the development of the Intertropical Convergence Zone, which increased air humidity, and the intensification of the East Asian monsoon, respectively. Both weather patterns emerged due to greater vertical growth of the Alps, Pyrenees, and Himalayas, which affected Eurasian climatic patterns.

## Ecological Concerns

Snakeheads can become invasive species and cause ecological damage because in many areas to which they are not native the absence of natural enemies gives them top-level predator status. Not only can they breathe air, but they can also survive on land for up to four days, provided they are wet, and are known to migrate up to 400 metres (1/4 mile) on wet land to other bodies of water by wriggling with their body and fins. *National Geographic* has referred to snakeheads as "Fishzilla" and the National Geographic Channel reported the "northern snakehead reaches sexual maturity by age two or three. Each spawning-age female can release up to 15,000 eggs at once. Snakeheads can mate as often as five times a year. This means in just two years, a single female can release up to 150,000 eggs."

"Since 2002, it has been illegal to possess a live snakehead in many US states, where they are considered a destructive invasive species." Virginia has criminalized the "introduc[tion]" of snakeheads into the state without specific authorization, although the relevant statute does not explain whether mere importation is sufficient to constitute "introduc[tion] into the Commonwealth" or whether instead release into the environment is required.

## As Food

Snakeheads are considered valuable food fish. Called *nga yant* in Burmese, it is a prized fish eaten in a variety of ways. In Vietnam, they are called *ca loc*, *ca qua*, or *ca chuoi*; it is prized in clay pot dishes and pickled preparations. Larger species, such as *Channa striata*, *Channa maculata*, and *Parachanna obscura*, are farmed in aquaculture. In the United States, chefs have suggested controlling the snakehead invasion by serving them in restaurants. In Indonesia, snakehead fish are called *ikan gabus*, served as the main parts of traditional dishes such as Betawi's *pucung gabus*, and considered to be a delicacy due to their rarity in wild and aquaculture, as they are harder to raise than other popular freshwater fish such as catfish and carp.