Channa in general
Channa, commonly known as Snakeheads, are primitive predatory fish and members of the family Channidae. They are a group of perciform (perch-like) fishes whose affinities are unknown, although recent studies on the molecular phylogeny of bony fishes consider snakeheads as most closely related to the labyrinth fishes (anabantoids) and the synbranchiform eels, which include the spiny eels.
The genus Channa contains 31 species that are native throughout Asia from are native from
southeastern Iran and eastern Afghanistan eastward through Pakistan, India, southern
Nepal, Bangladesh, Myanmar, Thailand, Laos, Malaysia, Sumatra, Indonesia,
Vietnam, Korea, and China northward into Siberia.
3 species of the closely related genera Parachanna are native to parts of Africa.
The different species of Channa vary in size considerably. The term dwarf snakeheads is coined by aquarists to describe a group of Channa species growing only 25 centimetres: Channa bleheri, Channa cachua, Channa orientalis and Channa andrao. These species are most suitable for keeping in an aquarium because of their size and their relative docile temperament.
Most of the species grow to a maximum length of 30-90 centimetres. Besides size, this intermediate category contains the most diversity in behaviour since some of the species are closely related to the dwarf species, and some relate more to the category of monster fish.
5 species (A. argus. C. barca, C. marulius, C. micropeltes and C. striata) can even grow up to 100 cm or even larger and can be considered monster fish that are barely suitable for aquaria.
Fossiles dated from 50 million years ago indicate an origin in the southern Himalayas (India and East Pakistan). From 15 million years ago and on, the animals have spread by the expanding intertropical climate zone to parts of Europe, Africa and larger parts of Asia.
Channa have an elongated body and are distinguished by their long dorsal fins large mouths full of teeth. They earn their common name Snakehead because their flattened shape and the scales on their heads that are reminiscent of the large epidermal scales on snakes.
Channa have gills to breathe water like most other fish. However subadults and adults can also breathe air to supplement their demand for oxygen. Snakeheads are in fact obligatory air breathers and must have air from the surface otherwise they will drown. Unlike many other airbreathing fishes, Channa have a series of cavities in the rear section of their head. These suprabranchial chambers are filled with folded tissues that have a high surface area, and allow oxygen change to occur directly between air and their blood. Unlike mammals, they lack a diaphragm and use water to exchange old air with fresh air each time they take a breath. Thus, their ability to breathe air when out of the water is limited. They appear to breathe air more frequently when swimming actively.
The genera Parachanna (native to parts of Africa) is described apart from the genera Channa because of a more primitive implementation of the airbreathing section.
Snakeheads are known to migrate over short distances over land to find other water basins, using the ability to breathe air. When moving over land they curve their body in an S shape first, before launching themselves forward by a powerful stretch. In high humidity conditions, Channa are able to survive from 2 up to 4 days out of the water. When placed in direct sunlight, however, they desiccate and perish in minutes to several hours. In contrary to what is believed, Snakeheads are not known to leave the water for any reason other than making their way back to the water after flooding. The only true Snakeheads to actively leave the water are some of the smaller species, C. gachau and C. orientalis, C. asiatica, and C. amphibeus, and still, there must be an obvious reason for leaving the water.
Snakeheads are able to live in varying water conditions. Some species are bound to a subtropical climate zone. For good health, these species require cooler water temperatures., at least for a seasonal period. Most snakeheads can tolerate a very large range of water parameters (temperature, PH, GH, level oxygen). However, they are very vulnerable in case of sudden changes.
Snakeheads are highly valued as food fish, particularly in India, southeastern Asia, China, and to a lesser extent in Africa. They have long been an important part of capture fisheries and, in recent decades, some species (C. maculata, P. obscura, C. striata, C. argus) have been utilized in aquaculture and a few used as predators to control the density of tilapiine fishes that are considered pest fishes in agricultural installations. Often local markets are stocked any day of the year with large amounts of Snakeheads. Sellers make use of the ability of the fish to survive for a long time in just a thin film of water. As a result, fresh fish can be offered any time of the day, which offers some benefits in a long hot day at a local market. Due to colonisation, in the last 100 years, Channa species have been introduced in many countries (Madagascar, Hawaii, Taiwan, Japan, Kazachstan, Turkmenistan, Uzbekistan and the Czech Republic).
It is reported that some Channa species possess anti-inflammatory properties. They are also known to have certain PUFAs that can regulate prostaglandin synthesis and also induce wound healing. The fish oil can have positive effects on cardiovascular diseases and cancers.
“Fish out of hell”
Currently, in the absence of natural top predators, the larger channa species are considered invasive and destructive to the local ecosystem. Larger species become sexually mature after 2 to 3 years (15-30 cm) already, can mate up to 2-5 times a year, and can produce up to 15.000 eggs at once. Especially C. Argus is considered to have the ability to double its population within 15 months and be able to flourish in most (fresh) water conditions.
Discovery of several large Channa species in water basins in the US made big news. The media had been set up to legitimate unpopular activities preventing the species from spreading to other water systems (like emptying or poisoning water basins). Several media painted a picture of Piranha like myths about monster fish that empty a lake, move on to the next to empty, hunting on dogs and children in the meantime on land. National Geographic launched a somewhat more fact-based documentary, Invasion of the Snakeheads, introducing the name “Fishzilla”. Last but not least, Hollywood filmmakers found inspiration and support to dedicate 2 horror movies to the monster fish.
Asian food markets (and the related stocking of fish in natural washbasins) have been reported as the root cause of the invasion of Channa in the US. Also, this makes the fish quickly available to aquarists. Specimens that outgrew the fishtank often ended up in the local ecosystem. Since 2002 in most states of the US it is forbidden to possess living Channa species.
Channa are predatory fish that prey in the juvenile stadium on plankton, insects and snails. While they grow the larger species switch towards a menu that consists mainly on fish, frogs, crabs, shrimps, small aquatic mammals and birds.
Before adulthood most Channa species hunt in groups. When becoming sexually mature they start a solitary life and develop a high level of aggression against their own species and other fish. When a couple has formed most species do not tolerate other fish.
Channa are not active swimmers and, when not feeding, tend to move only when surfacing for air. They spend a lot of time hovering in midwater or resting on the bottom within cover as ambush predators. Some larges snakeheads, however, live a more pelagic life and are far more active swimmers. All snakeheads are capable of powerful bursts of acceleration. They curve their body in an S-shape and launch themselves forward by stretching.
Parental care is a behavioural characteristic of Snakeheads. Both parents protect and guard their young vigorously. The majority of the species guard their eggs at the surface of the water. Some of the smaller species are mouthbrooder. Only some species are cave brooders.
Amongst specialist aquarists, Channa is a popular -oddball- aquarium fish. Snakeheads are elegant, alert, clever, restful and powerful fish, with lots of character. Their communication with conspecifics their hunting skills and breeding behaviour is fascinating. Some aquarist even specialize themselves by dedicating their large fish tank to the largest specimens. Sometimes they maintain a pet-like connection with their monster fish. Some rare and attractively marked species (like C. Barca) belong to the most expensive aquarium fish in the trade.
Some Snakeheads display considerable changes in colour pattern while growing. In the early days of classification of fish species, this formed a lot confusion since in that day’s colour was still considered a criterium for classification.
Besides some dwarf species, many juveniles are more attractively marked than adults. With age species often develop a browner, more drab look. Because of this phenomenon, some aquarists lose interest in the fish while it grows. Those considering their first purchase should be well aware of what they are getting into.
Because of its predatory nature, none of the Snakeheads are a suitable choice for a community tank. Most of the species will quickly empty a general community tank with smaller fish. Thus a dedicated aquarium is required for keeping snakeheads.
Aquarists have very diverse experiences when it comes to combining Channa species with other robust fish species. In general, most species are probably best kept alone. The level of tolerance towards other fish varies per species, but also seem to vary per specimen or specific situation. Combining Channa with other aggressive and territorial fish species, like members of the Cichlidae family is a strategy that does not work out well. A Channa that is intimidated will hide, try to escape the tank and refuse to eat.
Because of their size and relatively mild temperament most of the dwarf species can be combined with fish from 2/3 of their own length, as long their tank mates are not overly aggressive. Keep in mind that most of the members of the dwarf species are native to areas with varying water conditions, depending on the season. A seasonal drop of water temperature is required to maintain good health.
Medium sizes species
Many medium-sized channa (30-60 cm) should be combined with relatively fast swimming and robust fish, like larger cyprinids. The general opinion is that changes are best if the Snakeheads are not fully grown and the other fish are already settled. Newly introduced fish are often killed, even when they do not fit their mouth. Mostly however, the co-existence is temporary: When a couple is formed often all other fish are hunted and killed.
Large species (60 – 130 cm)
These species require a lot of space. Most private aquarium setup’s are just large enough to host only 1 or 2 adults. Young species often can tolerate conspecifics ans other robust fish very well. Newly introduced fish are often ripped apart instantly. Adult fish (especially formed couples) develop the maximum level of aggression. Most of the time they are last fish standing in an aquarium set-up.
Channa micropeltes – Giant Snakehead – Toman
Juveniles of Channa Micropeltes (meaning literally small-scaled snakehead) are found relative often in the aquarium trade and are in fact the most available snakehead species. Mostly they serve as cheap feeder fish for larger fish species and are sold under the incorrect name “Red Snakehead” Juveniles are indeed red coloured and live in groups. While looking at the bright coloured and quite docile juveniles, an unaware aquarist will not expect that this cute fishes will grow out to be a monster fish in just several months.
After 2 months the red colour dress will change to a white-yellowish base color, with 2 black longitudinal stripes and bright orange intermediate area in between. The tail section and the tail itself often contains a red spot. After a year this juvenile pattern is changed again for a pattern consisting somewhat drab black and white stains. Within 2 years they grow to a 50- 60 centimetres. From then on the growth rate stabilizes somewhat to the maximum of 106 cm and a weight of 22 kilograms.
Channa micropeltes is found in South-East Asia in Cambodia, Laos, Vietnam, Thailand, Borneo and Sumatra, Java and Singapore. The species is absent throughout India. Channa micropeltes is often confused with Channa diplogramma (also named Giant Snakehead), which is native to a small part of India.
Channa micropeltes is cultivated for human consumption, fish oil, medicine and for sport fishing. Besides that, the species has been used to reduce the large amounts of Tilapia in some water basins. Many governments have regulated cultivating because large amounts of feeder fish are used, including juveniles of species that are of commercial interest. In other countries nowadays, the species is considered highly invasive and destructive to the local ecosystem. A known population of Channa micropeltes exist in the waters of Florida (US), probably because of aquarists that set some specimens free.
Channa micropeltes is one of the few Channa species that is quite social and will continue to hang out and hunt in groups. It is a day-time feeder. Only if they reach sexual maturity (and form a couple) they isolate themselves and become aggressive to fish of the same species and to other fish.
Channa micropeltes have the largest teeth of all Channa. The enlarges canine teeth are knifelike, with to cutting edges in crosssection. This allows the shearing of prey.
Channa micropeltes is also one of the few Channa species that lives a pelagic life. Consequently they are not demanding on habitat and can live in rivers, lakes, swamps, streams and ditches. The ability of C. micropeltes to migrate over land is often exaggerated. Young specimens have the ability to “walk over land”. When they grow older a rounder shape of the belly is developed and the fish loses their ability to move over land completely.
The head of the female is not so large as the males. Females have a larger belly.
Because of the size, growth rate and the amount of food needed, this monster fish is only suitable for an aquarium of the size of public installation. A full-grown solitary Channa micropeltes will require an aquarium of at least 4 meters in length.
Reports are that young specimens combine reasonably well with other fish of similar same size, under the condition that they grow up with them. Newly added fish are often killed instantly, regardless of the size. Sooner or later other tankmates will probably meet a similar fate later on when a couple is formed. Most aquarist might not experience such event since at that time the fish has already outgrown most fish tanks. Combining other fish species might not be an issue at all since most of the private tanks setups are not large enough to host a couple of fish from this size anyway. Most people probably are not prepared to dedicate an aquarium of 4-6 meters to only one fish. If some want a fish like Channa micropeltes, C. Diplogramma seems a better choice since it has similar looks and behavior, but grows not as large. However. C. diplogramma is more rare in the trade, thus more expensive and the differences between this species are difficult to determine. Best advise is to buy this species only from a reliable source.
Besides the space needed, specimens larger than 50 cm can be quite dangerous. This fish can inflict serious injury not only to other fish, but also to its keeper. All movement in or around the fish tank will be considered food and cleaning the tank is quite a dangerous operation. The speed and power a Channa micropeltes launching their powerful jaws full of teeth can cause serious injuries to the owner (or their children).
Channa micropeltes in an aquarium becomes fully aware of his environment and will constantly monitor the owner and the food that will be offered. It is difficult to surprise this species since they see the food coming from far.
Being a Giant Snakehead does not automatically mean it will feel secure. The aquarium should contain area’s with dense vegetation with a lot of swimming place around. Several dark spots in the tank are appreciated. Empty tanks and strong light will be associated with open surface water and vulnerability for other predators and cause stress.
The temperature can be set between 24-28 degrees Celsius. General hardness and pH values are not critical – just avoid extremes.
A common misconception is that air-breathing fish live in stagnant, foul water in the wild and that clean water conditions are therefore not necessary in the aquarium. While most species can tolerate a wide range of water conditions, many fare poorly when water conditions deteriorate or undergo rapid changes (as in a massive water change). A lot of snakeheads are lost by beginner or advanced aquarist because of massive water changes and too rapid tank introduction. 15% water change a week should be ok. Good filtration is necessary, otherwise the amount of food will deteriorate the water fast.
Channa are fantastic escape artists. With their muscled body they can squeeze themselves through every gap and even lift the cover. A tight-fitting cover is a must.
Channa must breathe air otherwise they drown, which requires an air gap between the water level and the cover of the tank
Channa micropeltis have a lifespan of 10 to 15 years or longer.
Carnivorous. All live food will be eaten. Often the fish will accept frozen food, chunks of fish and even sinking meaty pellets. Don’t feed the fish beef or chicken meat. Some of the lipids from these meat source cannot be properly metabolised by the fish and may cause excess fat deposits and even organ degeneration. Young snakeheads need feeding on a daily basis while they are growing, but once they reach 45-90cm, 2-4 feeds a week will do fine. These fish do not require daily feeding as commonly believed. In fact, a fasting period for proper digestion is a healthy way to avoid internal bacterial growth and constipation which may likely result in bloating.
Grown fish should be fed using forceps to prevent injury – to the human.
Breeding this species requires a lot space and leaves the breeder with a lot of juvenile fish that are not valuable. There are no known breeding results from aquarists. However, this species is subject of many cultivating projects in South East Asia. The fish are sexually mature after 2 years when they reached 50-60 cm. When snakeheads mate, they are usually monogamous for an entire breeding season, and perhaps throughout their lifetimes.
The eggs are laid in the substrate and rise to the surface. The parents offer intensive and enduring care for the juveniles. When the offspring is free swimming, the parents will guide them through the water, in a way that is comparable to ducks and their fledgelings.
Possible intruders must face strong aggression from the parents who are guarding fry. Parent snakeheads guard their young vigorously. Channa micropeltes reportedly attacked, and in some instances killed, humans who approached the mass of young. Swimming people can be hurt badly. Spawning Giant Snakeheads have a fascinating behaviour pattern. The adults guard the balls of blood-red fry and push them, at intervals, to the surface to breath air. Spotting a ball of surfacing fry is an exciting sighting.
Patrick de Pijper