Northern Snakehead

The Northern Snakehead is a species of large carnivorous fish native to parts of the Koreas, China, and Russia. This species is often considered as food fish in several places within their natural range and are seldom kept as aquarium fish. Some of these fish that have been living in the natural waters of the U.S. might have been released by aquarium hobbyists, or those who hope to establish a local food resource. Presently it is becoming an invasive species in the United States.

Physical Description

Size: Usually reaches a length up to 100 cm (3 ft 3 in).

Weight: Large/adult specimens can weigh around 15 pounds.

Tail & Fins: They have a circular tail, a long dorsal fin with 49–50 rays, and an anal fin with 31–32 rays.

Teeth: Sharp villiform teeth are arranged in bands, with large canine teeth on the lower jaw and palatines.

Sexual Dimorphism: Not present, except that the males tend to be somewhat larger than the females.

Lifespan

The typical longevity status of the species in the wild is 3-8 years, with the average range being 5-6 years.

Classification of Species by Distribution

Based on their ranges, two subspecies of northern snakehead have been distinguished, viz. Channa argus argus originating from Korea and China, and Channa argus warpachowskii native to eastern Russia.

Habitat

The northern snakehead fish’s preferred habitats are stagnant water with mud substrate and aquatic vegetation, as well as muddy, slow-moving streams.

Behavioral Characteristics

These fish are active usually at late dusk and early night. It is a freshwater fish that use to facultative air-breathing by using a suprabranchial organ, as well as a bifurcated ventral aorta, which allows it to survive with aquatic and aerial respiration.

The species appears to be social and prefers to feed after sundown, usually in schools (groups), hunting amidst aquatic vegetation close to the shore. They are known to be highly aggressive towards their prey and usually hunt by chasing, attacking and biting. However, they have been seen dispersing during extreme cases of a scarcity of food.

These fish are able to produce a small array of sounds. Mature specimens have been seen emitting grunting noises while feeding, as also, a kind of clicking noise while rising to the water surface to breathe.

Diet

The northern snakehead is primarily piscivorous, living on other fish species, but has also been seen eating crustaceans, other invertebrates, and amphibians.

Reproduction and Life Cycle

These fish are capable of doubling their population in as less as 15 months. They can engage in mating and breeding throughout the year and reaches the age of sexual maturity within two or three years in the wild. During this time, they are around 30 to 35 cm (1 to 1.2 ft) long.

The females can lay up to 100,000 eggs a year. The eggs of this fish fertilize externally, which occurs in shallow water especially around dawn. The eggs are yellowish and spherical with a diameter of about 2 mm (0.079 in) and takes around one to two days for the baby fish to hatch out.

Before hatching, both the father and the mother keep guarding them until yolk absorption. The young of this species are capable of moving overland using wriggling motions.

Adaptations

1. By evolution, they have
   developed an unusual respiratory system that allows them to survive outside
   of water even for several days.
2. Northern snakeheads have the ability to wriggle their ways from
   one body of water to another over short distances.

Predators

Except for humans, these large fish, being at the top of the food web, do not have any specific predators within their environment. It is thought that they might be preyed upon by larger fish and birds, crocodilians, turtles, otters, etc.

Conservation Status

The exact population and conservation status have not yet been defined by the IUCN.

Interesting Facts

• Northern snakeheads are so
  used freshwater environment that
  they are unable to tolerate salinity over
  ten parts per million.
• A new concern has arisen
  due to the fish’s spread getting close to the Great Lakes of the US, which
  the species may enter and, resultantly, have a disruptive effect on that
  ecosystem.
• The world record size of
  the northern snakehead is 19.9 lb, with a length of 35.157 inches.