Asian small snake head
| Asian small snake head | ||||||||||||
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female Channa gachua TH3 / 02 |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Channa gachua | ||||||||||||
| Hamilton , 1822 |
The Asian small snakehead or dwarf snakehead ( Channa gachua ) is a small snakehead fish that does not exceed a length of 25 to 30 cm. According to the current state of science, Channa gachua is a species complex that seems to consist of at least 3 - 4 valid species. Like all Channa species, they rely on the intake of atmospheric air for breathing. This happens through an accessory respiratory organ, similar to that of the labyrinth fish .
Distribution and habitat
The distribution area of the Channa gachua complex extends over large parts of Asia, occurrences are from Iraq, Iran, Afghanistan, Nepal, Pakistan, India, Sri Lanka, Bangladesh, Bhutan, China, Myanmar, Thailand, Indonesia, Laos, Cambodia, Vietnam, Malaysia and Singapore reported. Depending on the place of origin, the individuals differ considerably in color, size and morphology.
In its range, Channa gachua occurs in almost all freshwater bodies.
Appearance
In general, Channa gachua is a typical representative of the snakehead fish that remains small. The body is elongated and cylindrical, the anal and dorsal extend over the back 2/3 of the body length. The caudal is round and relatively large. The paired ventrals serve as an important distinguishing feature from the very similar species Channa orientalis , which has no pelvic fins. The head is large and massive, the mouth is wide and equipped with small teeth, as is typical of predatory fish. In addition, Channa gachua has so-called pharyngeal teeth, which are located far back in the throat. The movable eyes are large and allow the species a very large field of vision.
It is difficult to distinguish the sexes from the outside; in some forms the males develop larger and more intensely colored unpaired fins.
Depending on where they were found, Channa gachua differ enormously in size, coloration and behavior - the palette ranges from small (up to 10 cm) forms that behave extremely aggressively (e.g. Channa gachua from Inle Lake ) to extraordinary large variants that reach a size of 30 cm and more (like Channa gachua from Khao Lak ). For maintenance in the aquarium, it is therefore extremely important to know where the animals were found. Important distinguishing features of the different variants include the color of the under-eye line, the general characteristics and intensity of the coloring and the final size achieved. The taxonomic status of the different variants in the C. gachua complex has not yet been sufficiently clarified.
Distribution, way of life and behavior
The C. gachua complex is found all over Southeast Asia in stagnant and slowly flowing fresh waters. The animals are extremely resistant to chemical contamination in the water of their habitats and can even be found in the sewers of plantations and factories.
Channa gachua feeds mainly on insectivores, but the prey pattern also includes small fish. Most of the species is an ambulance hunter, but the animals sometimes actively rummage for food. Prey animals are captured by thrusting, which is typical of predatory fish, and the suction effect created by the sudden opening of the large mouth supports the capture of prey.
During the courtship and mating season, the species behaves extremely aggressively within the species. Fights are started by extensive threats with a distended throat and splayed fins. If none of the opponents withdraws after these threatening maneuvers, the animals throw gushes of water at each other by winding body movements before they go on to the actual attack, in which the opponents bite into each other's mouth (tugging their mouths) and try to hit each other under water hold and prevent the necessary ascent to the surface of the water to breathe.
Reproduction
Channa gachua is a male mouthbrooder. Mating is preceded by violent arguments between the sexual partners, which often end in injuries such as torn fins and flaked scales. The mating itself takes place in a mutual entanglement of the partners, in which the sex products are released and fertilized. The tiny, oily eggs (diameter approx. 0.8 mm) float to the surface of the water after fertilization, where they are picked up by the male with the mouth and stowed in the throat. The male keeps the clutch, which, depending on where it was found, comprises between 30 and 250 eggs in its mouth for 5-14 days before the young hatch. It is often defended by the female against predators and territorial intruders. As soon as the fry hatch, they are released from the mouth by the male and immediately form a dense school in which they spend the first days and weeks of their lives. Both parent animals defend the young, with some forms the adult females are also supposed to produce eggs with which they feed the brood. Young Channa gachua grow very quickly, as is typical of a snakehead , and if fed well, they can be sexually mature after just a few months.
Keeping in captivity
Channa gachua is only rarely kept in aquariums and mostly by specialists, as the animals are mostly intolerant of other species and sometimes also intra-species. A pair of the smaller shapes can be kept in a tank with a front edge length of 80 cm (standard tank 112 l). The animals do not have any special demands on water quality and temperature, they are fed with insects (crickets, mealworms, flies, mosquito larvae), perch sticks and small fish (depending on the size of the snakehead, the food fish should be around 2–5 cm). The animals are generally not very particular about the food offered. Special attention should be paid to the design of the basin, which should contain many hiding spots so that the animals can at least partially avoid each other in the event of intraspecific aggression. Breeding in the aquarium is easy once a pair has been found. The best way to do this is to put a group of adolescent C. gachua (6–8 animals) together in a tank and remove the excess animals as soon as a pair has emerged. If the other animals are left in the tank, there is a risk that the breeding pair will injure or even kill them during the rearing of the young, since every intruder in the nesting area is mercilessly driven away.
It is very important that the aquarium is well covered. Even small openings for the supply lines of filters and heating rods can be fatal for the animals, as they are excellent and precise jumpers, like all snakehead fish. Depending on the nature of the soil, temperature, humidity and the presence of pets, they can survive outside the tank for a few hours, but jumping out is one of the most common causes of death when kept in captivity.
Taxonomy
The species was first described in 1822 under the taxon Ophiocephalus gachua by Francis Hamilton-Buchanan, since then the species has been subjected to multiple revisions and has been described as synonyms.
The current data suggests that Channa gachua is a complex of at least 3 -4 species that requires closer investigation.
Well-known variants of Channa gachua
In specialist circles, some forms of C. gachua with an exact location are common, for example:
- Channa gachua "Khao Lak" Growing tall (up to 30 cm) shape with blue under eyes and muted colors from Khao Lak.
- Channa gachua "Inlé Lake" Small (approx. 12 cm), extremely aggressive variant from the Inlé Lake
- Channa gachua "Thailand" Large (up to 25 cm) shape with a red line under the eyes; Quite colorful animals with calm, shy behavioral repertoire
- Channa gachua "Thailand 3/02" Up to 20 cm tall variant from Thailand; prefers habitats with running water; blue under eye line.
- Channa gachua "cinnamon plantation" Up to 15 cm. Sri Lanka
- Channa gachua "India"
- Channa gachua "Burma"
- Channa gachua "South India" up to approx. 15 cm, relatively peaceful for Ch. Gachua, also when caring for the brood
- Channa gachua "Bengal" up to approx. 25 cm, relatively well tolerated outside of the breeding season
literature
- Jörg Vierke: Band of robbers in the aquarium . ISBN 3440065839
Web links
- Asian small snakehead on Fishbase.org (English)
- http://www.snakeheads.org
- Channa gachua inthe IUCN 2013 Red List of Threatened Species . Posted by: Chaudhry, S., 2010. Retrieved January 25, 2014.
Individual evidence
- ↑ a b c d Channa gachua (Dwarf snakehead). In: www.iucnredlist.org. Retrieved June 27, 2016 .
- ↑ Maurice Kottelat: Nomenclature and type of Ophiocephalus marginatus and O. limbatus (Teleostei: Channidae) . In: Wildlife Heritage Trust of Sri Lanka (ed.): Journal of South-Asian Natural History . Vol 5, No. 1 , June 1, 2000, pp. 95-96 .