Overview

Brief Summary

Somphongs’s rasbora (Trigonostigma somphongsi) is a small, tropical, minnow-like cyprinid fish native to the Mae Khlong basin of Thailand.  It is one of four species in genus Trigonostigma.  It is considered critically endangered by the IUCN Red List of Threatened Species, as well as placed on the world’s 100 most endangered species list, due mainly to habitat degradation and development for farmland in addition to pressure from fishing.  Somphong’s rasbora is highly sensitive to vegetation loss; it lays its eggs at the base of aquatic plants in a spawning behavior unique to, and characteristic of members of this genus.  This species experienced a >90% population decline and in fact was considered extirpated as it was not been seen in the wild for more than twenty years.  More recently individuals occasionally show up among catches of other small fish shipped from Thailand to Europe for the aquarium trade indicating there are existing populations.  The localities and size of these populations are unknown but considered to be declining and presumably very local.  Breeding captive populations do exist, and if wild populations can be identified and their habitat restored and protected, it may be possible to support existing wild populations by reseeding them with captive stock.

(Vidthayanon 2011; Kottelat and Witte 1999; Malein 2012; IUCN 2012)

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Distribution

Range Description

The species was recorded from the lowland Mae Khlong basin near Ratchaburi in central Thailand.
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Thailand.
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Asia: Mae Khlong basin, Thailand.
  • Doi, A. 1997 A review of taxonomic studies of cypriniform fishes in Southeast Asia. Jap. J. Ichthyol. 44(1):1-33. (Ref. 26580)
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Physical Description

Size

Maximum size: 105 mm TL
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Max. size

10.5 cm TL (male/unsexed; (Ref. 2059))
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Found in lowland marshes with aquatic plants. The species is dependent upon underwater plants as it lays sticky eggs on the lower arts of the plants. If aquatic plants are lost, then it is likely that populations will decline.

Systems
  • Freshwater
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Environment

benthopelagic; freshwater; pH range: 6.0 - 6.5; dH range: 8
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
CR
Critically Endangered

Red List Criteria
A2ac

Version
3.1

Year Assessed
2013

Assessor/s
Vidthayanon, C.

Reviewer/s
Kottelat, M. & Allen, D.J.

Contributor/s

Justification
This fish is recorded from the lowland Mae Khlong basin near Ratchaburi in central Thailand. It was considered (but not formally assessed for the IUCN Red List) as Extinct in the Wild for several years as a result of habitat loss and degradation, and fishing, but individuals appear occasionally in shipments of other small fishes for the aquarium trade in Germany and Japan.

It appears that the species is still present in the wild within its previous range, but the location of the specimens found in the aquarium trade is not currently known. The species is assessed as Critically Endangered based on its previous population decline of more than 90%.

Further research is needed to confirm the source of remaining specimens from the wild and should benefit from conservation effort to protect habitat and prevent further exploitation.
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Population

Population
This fish has been collected in the past for the aquarium trade. It had not been seen for twenty years, but now occurs occasionally in mixed catches for the aquarium trade. There are some in captivity and it is occasionally bred in aquaria.

Although considered possibly extirpated, it is apparently still present in the wild, but probably in localised populations.

Population Trend
Decreasing
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Threats

Major Threats
Habitat degradation from wetland conversion for farmland and urbanization, particularly due to the loss of vegetation. The species may also be taken in mixed catches.
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Critically Endangered (CR) (A2ac)
  • IUCN 2006 2006 IUCN red list of threatened species. www.iucnredlist.org. Downloaded July 2006.
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Management

Conservation Actions

Conservation Actions
Habitat and population surveys are needed, and restoration of wetlands is important for this species. Ex-situ conservation from captive stock is an option to support remaining wild populations. The location of the wild source of specimens should be identified and the location protected.

The species is listed in the Thai Red Data book as threatened.
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Wikipedia

Trigonostigma somphongsi

Trigonostigma somphongsi is a species of ray-finned fish in the genus Trigonostigma. It is endemic to Thailand. It is threatened by habitat loss.[1]

References[edit]

  1. ^ a b Vidthayanon, C. (2011). "Trigonostigma somphongsi". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 7 May 2014. 
  2. ^ Froese, Rainer and Pauly, Daniel, eds. (2006). "Trigonostigma somphongsi" in FishBase. April 2006 version.
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