Threadfish

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Threadfish
Trichopodus trichopterus with the clearly recognizable, eponymous fin rays

Trichopodus trichopterus with the clearly recognizable, eponymous fin rays

Systematics
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Climbing fish species (Anabantiformes)
Subordination : Labyrinth fish (Anabantoidei)
Family : Osphronemidae
Subfamily : Threadfish
Scientific name
Trichogastrinae
Bleeker , 1879

Nine species of South and Southeast Asian labyrinth fish are known as thread fish , which, in addition to accessory breathing with their labyrinth organ, have another common characteristic: long, extended first ventral fin rays with which they are able to absorb touch and taste stimuli. These skills support them in spatial orientation, in searching for food and in intra-species communication. For a long time the threadfish were not considered a scientific taxon, but the two genera of the threadfish were assigned to the subfamily Luciocephalinae together with others .

Systematics

In this composition, however, this was not monophyletic , but divided into two clades . A clade consisting only of mouthbrooders has eggs in common, which have a spiral structure on the surface that probably serves as a guidance system for the sperm. The other clade consists of the two species of threadfish and is more closely related to the Macropodusinae than to the spiral egg clade.

In the fifth edition of Fishes of the World , a standard work on fish systematics, the threadfish were therefore introduced as the fifth subfamily of the Osphronemidae . The scientific name Trichogastrinae was available, which was first used in 1879 by the Dutch ichthyologist Pieter Bleeker . The scientific fish database Catalog of Fishes also places the genera Trichogaster and Trichopodus in the subfamily Trichogastrinae.

Genera and species

Traditionally, threadfish are divided into two genera based on their morphometry and geographic distribution:

Four smaller species, "Western threadfish" (genus Trichogaster , syn .: Colisa Cuvier, 1831) from South Asia (India and Burma):

Five larger species, "Eastern threadfish" (genus Trichopodus ) from Southeast Asia, widespread in the Indonesian region, whose original occurrence can no longer be determined because they were spread from Thailand to the island world of the Philippines before their scientific discovery as a human food source:

Reproductive behavior

All threadfish reproduce according to a largely identical basic pattern. The males build a foam nest on the surface of the water or under the leaves of floating plants , which consists of air bubbles coated with a saliva-like secretion . Trichopodus species often use other building materials, such as parts of plants. Under this foam nest, which is constantly being worked on, the male advertises until a female who is ready to mate appears, with whom it spawns directly under the foam nest according to a typical ritualized behavior . The relatively small eggs are lighter than water (swimming eggs) and rise up into the foam nest. When the act of spawning is over, the female leaves the nesting area. The parental care is carried out exclusively by the male ( father family ). At a water temperature of 24 to 28 ° C, very small larvae hatch after about 24 to 30 hours . They carry a relatively large yolk sac with an oil content that keeps them under the foam nest thanks to its buoyancy. Larvae flushed from the nest area are picked up by the male with the mouth and spat back into the nest. Between the third and fifth day of life, the fast-growing juvenile fish swim free and immediately eat independently. They leave the immediate nest area, whereupon the brood care of the male goes out.

Importance to humans

“Eastern threadfish” are of considerable importance for human nutrition in Southeast Asia . On markets they regularly represent a considerable part of the fresh fish supply. Due to their special breathing, it is possible to offer them alive for a very long time. For this reason, they were naturalized all over mainland Southeast Asia and on many islands in this area. For evolutionary biologists and behavioral researchers , thread fish, like all labyrinth fish in general, are an instructive area of ​​research.

Since the end of the 19th century, threadfish have been very common and popular aquarium fish . Several color varieties were bred from three Trichogaster species (all except T. fasciata ) and the spotted threadfish , which are part of the standard range of the aquarium fish trade.

literature

  • Kokoscha, M. (1998): Labyrinth fish . Publishing house Eugen Ulmer, Stuttgart. ISBN 3-8001-7431-6 .
  • Kottelat, M. (1989): Zoogeography of the fishes from Indochinese inland waters with an annotated check-list . Bulletin Zoölogisch Museum, Universiteit van Amsterdam v. 12 (no. 1): 1-55.
  • Roberts, TR (1989): The freshwater fishes of western Borneo (Kalimantan Barat, Indonesia) . Memoirs of the California Academy of Sciences No. 14: i-xii + 1-210.
  • Tan, HH and PKL Ng (2005): The labyrinth fishes (Teleostei: Anabanatoidei, Channoidei) of Sumatra, Indonesia . The Raffles Bulletin of Zoology Suppl. No. 13: 115-138.

Individual evidence

  1. ↑ Lukas Rüber, Ralf Britz, Rafael Zardoya: Molecular Phylogenetics and Evolutionary Diversification of Labyrinth Fishes (Perciformes: Anabantoidei). In: Syst. Biol. 55 (3) 2006, pp. 374-397. ISSN  1063-5157 doi : 10.1080 / 10635150500541664
  2. ^ Joseph S. Nelson, Terry C. Grande, Mark VH Wilson: Fishes of the World. Wiley, Hoboken, New Jersey, 2016, ISBN 978-1118342336
  3. ↑ Trichogaster in the Catalog of Fishes (English)
  4. ↑ Trichopodus in the Catalog of Fishes (English)
  5. ^ Low, BW, Tan, HH & Britz, R. (2014): Trichopodus poptae, a new anabantoid fish from Borneo (Teleostei: Osphronemidae). Ichthyological Exploration of Freshwaters, 25 (1): 69-77.