HomeFreshwater aquarium fishBarbs, danios & rasborasHarlequin rasbora Harlequin rasbora (Trigonostigma heteromorpha) Scientific name: Trigonostigma heteromorpha Duncker, 1904 The Harlequin rasbora (Trigonostigma heteromorpha) is a freshwater fish of the family Cyprinidae that grows to about 4 cm (1.6 in). It is easy to keep and peaceful, suits community aquariums and needs a tank of at least 55 L (15 US gal), water at 22–25°C (72–77°F) and a pH of 5.0–7.0. Native range: ASIA; Forest streams and rivers in Thailand, Malaysia, and Sumatra. Harlequin rasbora care at a glanceCare levelEasyTemperamentPeacefulCommunity tankExcellentAdult size4 cm (1.6 in)Minimum tank55 L (15 US gal)Temperature22–25°C (72–77°F)pH5.0–7.0Hardness5–12 dGH (89–214 ppm)DietOmnivore. Accepts flakes, frozen foods and live foods. BiologyColor pattern reddish, pinkish or orange body with a conspicuous black stripe from below dorsal-fin origin to middle of caudal-fin base and usually broadened anteriorly so as to have a triangular or hatched shape. Incomplete lateral line reduced to 6-9 pores. No barbels. Branched anal rays, 5.Source: FishBase, licensed CC BY-NC 4.0. Species factsScientific nameTrigonostigma heteromorphaFamilyCyprinidae (Minnows or carps)OrderCypriniformes (Carps)ClassActinopterygii (Ray-finned fishes)Maximum length5.0EnvironmentFreshwater;; pH range: 5.0 - 7.0; dH range: 5 - 12 benthopelagicClimateTropicalDistributionAsia: Thailand (Narathiwat southwards) to Sumatra, Indonesia.Conservation status (IUCN)Not EvaluatedThreat to humansHarmlessUsesAquarium: highly commercialResilienceHigh, minimum population doubling time less than 15 months (Preliminary K or Fecundity.) More barbs, danios & rasborasDwarf rasboraBoraras maculatusBlackline rasboraRasbora borapetensisGiant danioDevario aequipinnatusPearl danioDanio albolineatusClown rasboraRasbora kalochromaBrilliant rasboraRasbora einthoveniiSee all barbs, danios & rasboras Can it live with...?Harlequin rasbora and Arulius barbHarlequin rasbora and Blackline rasboraHarlequin rasbora and Brilliant rasboraHarlequin rasbora and Clown barbHarlequin rasbora and Clown rasboraHarlequin rasbora and Coppernose barbHarlequin rasbora and Dwarf rasboraHarlequin rasbora and Giant danioHarlequin rasbora and Greater scissortailHarlequin rasbora and Pearl danioHarlequin rasbora and Striped barb SourcesTaxonomy, distribution and biology data: FishBase (Froese, R. and D. Pauly, eds.), licensed CC BY-NC 4.0. Aquarium care parameters compiled, checked and converted to metric and imperial units by Guppies.za.net.Last updated 28 September 2026