The Harlequin Rasbora is easily identified by its trademark triangular mark on its body. It is the most well-known and popular aquarium fish among the Rasboras, especially in community tanks. The species is a native of Malaysia, Singapore, Sumatra and Southern Thailand. It inhabits in streams and other waterbodies in peat swamp forests. It is a Category I species, adjuring a fair price but in huge numbers.
This species is collected through a laborious process of manual scooping of individual specimen or in groups. Even though the Harlequin Rasbora is a schooling species, the rough terrain of the swamp forests and the crowded vegetation make spawning strenuous. However, middlemen will seek out keen helpers such as the school children who enjoys catching these fishes, in more disturbed areas such as Pulau Bintan where the fishes can be captured in large amounts, and earn extra pocket money. These middlemen would then gather the specimens and sell to the dealer collectively. Unlike the Bala Shark, Arowana and Clown Loach, this species are easier to spawn in shallow waters instead of large rivers which involves the use of boats and fishing experts.
On contrary to the other species introduced, the Harlequin Rasbora is not endangered as of yet. However, it is important to be forward-looking as there are enough reasons to be concerned about its survival state in the future. As the primary fishing period for this species is during low water seasons, this fishes usually decline due to the lack of water after the period. Hence, it calls for attention as it is anticipated that other than the aquarium fish trade, the fast decline of swamp forests will threaten its survival.