Epalzeorhynchos bicolor 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Cypriniformes Cyprinidae

Scientific Name: Epalzeorhynchos bicolor (Smith, 1931)
Common Name(s):
English Redtail Sharkminnow, Redtailed Black Shark, Red-tailed Labeo, Red Tailed Shark, Redtail Shark

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii,v)+2ab(iii,v) ver 3.1
Year Published: 2011
Date Assessed: 2011-02-23
Assessor(s): Vidthayanon, C.
Reviewer(s): Parenti, L., Kottelat, M. & Smith, K.
This species is endemic to Thailand, and has been recorded from the lower Mae Khlong, Chao Phraya and Bangpakong basins. Previously it was thought to be Extinct in the Wild and it is believed to be extirpated across its range apart from one location (C. Vidthayanon pers. comm.) in the Chao Phraya (extent of occurrence and area of occupancy both less than 10 km²). Historically it has been threatened by high levels of harvesting for the aquarium trade, but now this is supplied entirely by captive bred individuals. Currently the major threat to the wild population is pollution from agricultural and domestic sources. More research is needed on this species' presence across its range and a reintroduction programme is recommended.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to Thailand, where it is known from the lower Mae Khlong, Chao Phraya and Bangpakong basins. Formerly it was thought to be Extinct in the Wild, but recent information confirms that the species is still extant (C. Vidthayanon pers. comm.), but very localised, in the Chao Phraya. It is reported to be extirpated in the Mae Khlong and Bangpakong basins but this needs further investigation.
Countries occurrence:
Additional data:
Estimated area of occupancy (AOO) - km2:5-10
Number of Locations:1
Lower elevation limit (metres):10
Upper elevation limit (metres):50
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:It is reported that the species has disappeared from many parts of its range. Large numbers are exported annually from Thailand, all now from captive bred sources.
Current Population Trend:Unknown
Additional data:
Continuing decline of mature individuals:Yes

Habitat and Ecology [top]

Habitat and Ecology:This fish inhabits lowland streams with rocky or sand gravel bottoms.
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: This is a hugely popular aquarium fish, all individuals are now captive bred.

Threats [top]

Major Threat(s): The reasons for the decline in the wild population of the species are not well known. The aquarium fish trade has been accused of driving the species to local extirpation because of very selective overfishing (over the past 40 years), but there is no documented evidence for this (Kottelat and Whitten 1996). Habitat modification may be the more likely cause of population declines in this case (M. Kottelat pers. comm. 2011). In the 1970s, many dams were constructed in Thailand and these probably severely impacted several large basins in the region. Large swamp areas have also been drained. Habitat degradation and change (including pollution from farmland and domestic sources, infrastructure development such as road building and dams causing loss of habitat and changing in flow regimes and siltation due to agriculture) are now the main threats to this species.

Conservation Actions [top]

Conservation Actions: Species recovery action plan and reintroductions (to extirpated locations) are recommended for this species. The species is widely commercially captive bred but this stock may not be genetically suitable for re-introductions so a conservation specific ex-situ conservation breeding programme is recommended.

Citation: Vidthayanon, C. 2011. Epalzeorhynchos bicolor. The IUCN Red List of Threatened Species 2011: e.T7807A12852157. . Downloaded on 16 August 2018.
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