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 thoughout 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 centimeters: 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 centimeters. Besides size, this intermediate category contains the most diversity in behaviour since some of the species are closer related to the dwarf species, and some relate more to the category of monsterfish.
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 monsterfish 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 end 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 breath water like most other fish. However subadults and adults can also breath 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 waterbassins, using the ability to breath 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 dessicate 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 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 change.
Snakeheads are able to live in varying waterconditions. Some species are bound to a subtropical climatezone. For good health these species require cooler watertemperatures., at least for a seasonal period. Most snakeheads can tolerate a very large range of waterparameters (temperature, PH, GH, level oxygen). However, they are very vulnerable in case of sudden changes.
Snakeheads are highly valued as foodfish, 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 density of tilapiine fishes that are considered pestfishes in agricultural installations. Often local markets are stocked anyday 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 anytime 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 absence of natural toppredators 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) waterconditions.
Discovery of several large Channa species in waterbassins in the US made big news. The media had been set up to legitimate unpopulair activities preventing the species from spreading to other watersystems (like emptying or poisoning waterbassins). Several media painted a picture of Piranha like myths about monsterfish 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 documentairy, Invasion of the Snakeheads, introducing the name “Fishzilla”. Last but not least, Hollywood filmmakers found inspiration and support to dedicate 2 horrormovies to the monsterfish.
Asian foodmarkets (and the related stocking of fish in natural fishbassins) have been reported as the rootcause of the invasion of Channa in the US. Also, this make 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 a S-shape and launch themselves forward by stretching.
Parental care is 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 holebrooders.
Amongst specialist aquarists Channa is a popular -oddball- aquariumfish. Snakeheads are elegant, alert, clever, restful and powerful fish, with lots of personality. Their communication with conspecifics their hunting skills and breeding behaviour are fascinating. Some aquarist even specialize themselves by dedicating their large fishtank to the largest specimens. Sometimes they maintain a pet-like connection with their monsterfish. Some rare and attractively marked species (like C. Barca) belong to the most expensive aquariumfish in the trade.
Some Snakeheads display considerable changes in colour pattern while growing. In the early days of classification of fishspecies this formed a lot confusion since in that days colour was still considered a criterium for classication.
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 phenomen 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 communitytank 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 too 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 temporarely: 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. Adultfish (especially formed couples) develop the maximum level of aggression. Most of the time they are last fish standing in an aquarium set-up.
Channa diplogramma – Malabar slangekopvis
Young of Channa diplogramma (meaning literally doublestripe) are red coloured and live in groups. De attractive litte fish are nice to see and appear quite docile. An unaware aquarist probably cannot suspect that this cute babies will become a rivermonster within a some months. Accordingly to their name after two months the fish change their pattern for a white-yellowish basecolour, with two horizontal black stripes over the body. In the middle often with a bright orange glow. After a year this pattern will be changed again over a drab black and white pattern.
Channa diplogramma will grow 44 cm maximum. Physical features and behaviour are almost identical to C. Micropeltes. Until 2011 it was considered a synonym. It can be distinguished from all other species by:
- a greater pre-anal length (55.66 mm vs. 50.64 mm in C. micropeltes)
- lesser body depth (mean 15.60 mm vs. 20.05)
- fewer cheek scales (16-20 vs. 23-25)
- fewer total vertebrae (53-54 vs. 57)
- more caudal-fin rays (15-17 vs. 14)
- possessing 103-105 lateral line scales (vs. 36-91)
Channa diplogramma is endemic to parts of South India, in Kerala en Tamil Nadu.
Behaviour and requirements are very similar to Channa micropeltes.
Since Channa diplogramma grows considerably smaller then Channa micropeltes it makes it slightly more suitable for the aquarium. At the same time, they are quite rare in the trade, which makes demand and prices higher. You would not be the first paying much while ending up with a Channa micropeltes that grows far to large for the aquarium. Advice is to buy this fish only from a respectable trader or when the orgin of the fish is known.
Patrick de Pijper
Ben Lee, Amiidae.com