Spotfin betta  (Betta macrostoma)

Classified as Vulnerable (VU) on the IUCN Red List (1).

The spotfin betta is a small and attractively marked freshwater fish, and gains its common name from the black ‘eye’ spot on the rear of the male’s dorsal fin. In breeding colouration, the adult male spotfin betta is reddish-brown in colour, with a black area below the eye and a large red blotch on the gill cover. The tail fin has vertical black and red bands and a thin white margin, while the dorsal fin, which is set quite far back on the body, bears a series of small spots in addition to the eye spot. The long anal fin has a broad dark margin (2) (3) (4). There may also be two prominent black stripes running along each side of the body. The female spotfin betta also has two black stripes, but is less brilliantly coloured than the male, and also lacks the facial markings and the eye spot on the dorsal fin (2) (5). Juveniles have two rows of spots on the body (2).

The spotfin betta occurs in Brunei and northern Sarawak, Borneo (1) (2) (4) (5).

This species is found in freshwater, and has been reported to inhabit cool, fast-flowing rivers, shallow pools and waterfall pools in rainforest (1) (2) (3) (4).

Little information is available on the biology of the spotfin betta. It is likely to be a predator, and may eat other fish (2). Like many Betta species, the spotfin betta is a mouthbrooder, the male incubating the eggs and brooding the young in its mouth for a number of weeks (2) (3) (5) (6). This strategy of parental care may not only protect the eggs and young from predation, but also from strong water currents (6). The young spotfin betta reaches sexual maturity at around six months (2).

Little is known about the threats to the spotfin betta. The species appears in the pet trade (2) (3), but the impacts of this on the wild population are unknown. Many freshwater fish in South East Asia have been exploited for the live aquarium trade, and are also under threat from habitat loss through deforestation (7). The spotfin betta was believed extinct until its ‘rediscovery’ in Brunei in 1981 (8), but its current wild status is unknown.

There are no specific conservation measures currently known to be in place for the spotfin betta. Conservation measures suggested for other freshwater fish in the region include captive breeding, public education, sustainable harvesting, and the protection and restoration of rainforest habitat (7). Further research and survey work are also likely to be needed for the spotfin betta before this attractive fish can be adequately protected.

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about the spotfin betta and its conservation see:

• IUCN Red List:
  http://www.iucnredlist.org
• Fishbase:
  http://www.fishbase.org/Summary/SpeciesSummary.php?id=12039