Eleutheronema tetradactylum
| Eleutheronema tetradactylum | ||||||||||||
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Eleutheronema tetradactylum |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Eleutheronema tetradactylum | ||||||||||||
| ( Shaw , 1804) |
Eleutheronema tetradactylum is a marine fish from the threadfin family. Along with Polydactylus quadrifilis , it is the largest of them. It is very important in commercial fishing. He is also a proterandric hermaphrodite , he changes at an age of about one to two years from male to female.
description
Eleutheronema tetradactylum reaches a maximum length of about 2 meters. The head is usually 29% of the standard length and the caudal fin is 32%. The first dorsal fin consists of 8 hard rays . The second dorsal fin, clearly separated from the first, has a hard ray and 13 to 15 soft rays . The anal fin , consisting of 3 hard and 14 to 16 soft rays, is symmetrical to the second dorsal fin. Both are concave. The large caudal fin is deeply split. The lowest four rays of the pectoral fins are elongated like threads. On these “threads” there are sensory cells with which the fish scans the ocean floor. Compared to many other large threadlossers , the body of Eleutheronema tetradactylum appears slimmer and less humped. The mouth is strongly underneath and reaches far behind the eyes, so that a strange "overbite" arises.
Distribution, habitat and biology
Eleutheronema tetradactylum inhabits the northern Indian Ocean and parts of the West Pacific . The distribution area extends from the Horn of Africa over the South and Southeast Asian coast, the Malay Archipelago and the Philippines to the north coast of Australia . The animal prefers shallow waters near the coast with a soft, muddy bottom. There the benthopelagic fish feed on crustaceans and other invertebrates as well as small fish such as sardines . Larvae feed mainly on small crustaceans, such as copepods , and crab larvae. The fish lives in small, loose groups. Adult specimens climb rivers during winter. Juvenile specimens inhabit estuaries.
It is also a proterandric hermaphrodite . At an age of one to two years and a length of 25 to 65 centimeters, the sex change takes place from male to female. Accordingly, all fry are males.
use
This fish plays an important role in the commercial fisheries of many South and Southeast Asian countries as well as in northern Australia. He is mainly caught with nets. It is also kept in aquaculture . This species also has a certain importance for sport fishermen .
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literature
- Roland J. McKay: An annotated and illustrated catalog of polynemid species known to date. FAO Species Catalog for Fishery Purposes. No. 3rd FAO Rome 2004. ( PDF )
Individual evidence
- ↑ a b c d e Eleutheronema tetradactylum on Fishbase.org (English)
- ↑ a b c d Roland J. McKay: An annotated and illustrated catalog of polynemid species known to date. FAO Species Catalog for Fishery Purposes. No. 3rd FAO Rome 2004. ( PDF )
Web links
- Eleutheronema tetradactylum on Fishbase.org (English)