[Articoli scientifici] Channa bleheri

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US Geological Survey / foto di USGS
Tratto da: Snakeheads (Pisces, Channidae): A Biological Synopsis and Risk Assessment
 Di Walter R. Courtenay,James David Williams



Reprinted with permission from Jorg Vierke from: Vierke, Jorg. 1991a. Ein farbenfroher neuer schlangenkopffish aus Assam Channa bleheri spec. nov. Das Aquarium 259:21.

Original description: Channa bleheri Vierke, 1991a:20-24. Ein farbenfroher neuer Schlangenkopffisch aus Assam Channa bleheri spec. nov. Das Aquarium 259:20-24. Type locality: upper part of Dibru River, near Guijan, Brahmaputra River basin, northeastern Assam, India. Holotype: ZFMK 16555. Paratype: ZFMK 16556.

Synonyms: No synonyms.

Common name: rainbow snakehead.


         Native range: Endemic to the Brahmaputra River basin, Assam, India (Musikasinthorn, 2000).

         Introduced Range: No introductions known.

         Size: To about 20 cm.

         Habitat preference: Forest streams, ponds and swamps in tropical rainforest conditions (Musikasinthorn, 2000).

         Temperature range: Unknown, except preferred habitat and known range is subtropical.

         Reproductive habits: No specific information concerning wild populations. Vierke (1991b), however, described reproductive behavior in aquaria in detail. He noted that females are smaller than males of the same age, and that males grow faster than females. A male selects the nesting site, but it is the female that appears to initiate courtship behavior. Two days prior to spawning, there is frequent body contact between male and female, with the two wrapping around each other. This behavior increases at spawning, near the surface, and the spawning act can last up to 30 seconds.

         The eggs released are transparent and float to the surface. They are small, round, and 0.9-1.1 mm in diameter. An oil globule, about 0.6-0.7 mm in size, is present in each egg. The egg mass, with eggs close together, appears to be made of foam. Both the male and female initially tend the egg mass and display an interesting behavior. They take the eggs into the oral cavity and expel them through the gills, presumably to remove materials that may settle on egg surfaces. The eggs adhere to each other at the surface. Following hatching, both parents guard the larvae.

         The young remain around the parents, often with body contact between them. Young can often be found on the heads of parents, appearing to be feeding on mucus. They appear to nip the parents, and removal of young from parents at this stage seems to slow growth of the separated individuals.

         Feeding habits: No information concerning wild populations, but likely a carnivorous predator as an adult. Vierke (1991b) noted that in aquaria, rainbow snakeheads will feed on worms similar to bloodworms. When fed guppies (Poecilia reticulata), they will eat guppies they can easily catch, but typically tire of chasing this prey, eventually tolerating their presence.

         Characters: No area of scales in gular region. No pelvic fins. Dorsal rays 36-37; anal rays 24; predorsal scales 6-7; lateral line scales 45-46. One or 2 large scales on undersurface of lower jaw.

         Live adults have large irregular red or orange spots (white in preserved specimens) that sometimes coalesce (Musikasinthorn, 2000). This is the most colorful of all snakehead species. Newly hatched larvae are colorless. When they reach a length of 1 cm, the dorsum and sides of the body becomes "canary" yellow, with a dark bar on the head, angled from the tip of the lower jaw, through the eye, to the upper margin of the operculum; the ventral side is colored smoke gray to black. As young continue to grow, their color becomes more pale and an ocellus appears on the posterior part of the dorsal fin. Later they begin to change to adult coloration (Vierke, 1991a).

         This species appears to be most closely related to Channa burmanica (Peter Ng, personal commun., in Vierke, 1991b). They differ in several characters. Channa burmanica has 51 lateral line scales, 28 anal rays, and 8 predorsal scales, whereas these counts in C. bleheri are 45-46, 24, and 6-7, respectively. The rainbow snakehead also has a longer caudal peduncle than C. burmanica with 9 scales from the posterior end of the anal fin to the caudal fin base in C. bleheri and 4+2 in C. burmanica (Vierke, 1991b).

         Commercial importance in the United States: This species is sometimes listed on aquarist-oriented websites and has been available for sale through aquarium fish retailers. Because of its attractive coloration, it appears to have been increasing in popularity as an aquarium species. An aquarium fish dealer in Kentucky was found to be selling this species illegally, having imported them from a supplier in Atlanta, Georgia, where snakeheads are also illegal (Major David Casey, personal commun., 2002).

         Commercial importance in native range: This species is caught commercially for the aquarium fish trade (Ralf Britz, personal commun., 2002) and is not known to be cultured for this purpose.

         Environmental concerns: If released into U.S. waters, it could become established in subtropical Florida, Hawaii, perhaps southeastern Texas, and thermal springs and their outflows in western states. Probably predacious on other fishes.