Snakehead (fish)
The snakeheads are members of the freshwater perciform fish family Channidae, native to parts of Africa and Asia. These elongated, predatory fish are 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, which are primitive forms of labyrinth organs, that develop when they grow older.[1] The two extant genera are Channa in Asia and Parachanna in Africa, consisting of more than 50 species.
They are valuable as a food source and have become notorious as an intentionally released invasive species. These fish have been kept as pets but as they get larger, people let them go into ponds, lakes, and rivers, making these fish invasive.
The various species of snakeheads differ greatly in size; dwarf snakeheads, such as Channa orientalis, do not surpass 25 cm (10 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.[2]
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 rodents such as rats are eaten.
The Channidae are well represented in the fossil record and known from numerous specimens. They 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 and Anchichanna kuldanensis , have both been found in the Middle Eocene of Pakistan.[3][4] By 17 Mya, during the Early Miocene, Channidae had spread into western and central Eurasia, and by 8 Mya, during the late Tortonian, they existed throughout Africa and East Asia.[5] 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. Both weather patterns emerged due to greater vertical growth of the Alps, Pyrenees, and Himalayas, which affected Eurasian climatic patterns.[5]
Snakeheads can become invasive species and cause ecological damage because, in many areas to which they are not native, the absence of natural enemies give them apex predator status. Not only can they breathe air, but they can also survive on land for up to 4 days, provided they are wet, and are known to migrate up to 400 m (1/4 mi) on wet land to other bodies of water by wriggling with their bodies and fins.National Geographic has referred to snakeheads as "fishzilla"[6] 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."[7]
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