Purple Harlequin Rasbora Care Guide - Aquarium Setup, Diet & Breeding

The Purple Harlequin Rasbora is a selectively coloured form of the classic Harlequin Rasbora, prized for its rich violet, plum or purplish-copper body tones. Its most recognisable feature is the bold, wedge-shaped black marking on the rear half of the body, set against a warm metallic base colour. Depending on lighting and individual genetics, the purple colour can range from subtle lavender to a deep wine-like sheen.

This is a small, active but notably peaceful schooling fish. Groups move confidently through the middle and upper levels of the aquarium, often changing direction together without the nervousness seen in some smaller schooling species. Their social behaviour is most impressive when they are kept in a properly sized group, where they spend less time hiding and display more natural interaction.

In the wild, Harlequin Rasboras are associated with calm, shaded waters beneath overhanging vegetation. Fallen leaves and submerged branches often tint their habitat amber with tannins, while dense marginal plants provide cover. The species is adapted to gentle currents and clear to tea-coloured water rather than powerful flow.

Although the Purple Harlequin Rasbora is a cultivated colour variety rather than a separate species, it retains the same peaceful nature and general biology as the natural form. Its compact size, attractive pattern and active schooling behaviour have made it one of the most popular rasboras for planted community aquariums.

Trigonostigma heteromorpha is native to Southeast Asia, occurring in parts of southern Thailand, Peninsular Malaysia, Singapore, Sumatra and nearby areas of Borneo. It inhabits slow-moving, soft, tannin-stained forest streams, peat swamps and quiet tributaries.

A group should be kept in an aquarium of at least 60 litres, with a footprint of approximately 60 × 30 cm or larger; a longer tank is preferable because it gives the shoal more swimming space. Use gentle filtration and subdued lighting, with live plants, floating cover, driftwood and leaf litter creating shaded areas and visual security. A dark, fine-grained substrate helps bring out their colours, while open swimming areas should be left between plant groups. Stable, clean water and mild circulation are more suitable than strong turbulent flow.

Up to 5 cm (2 inches) in adult length. Females are usually slightly larger and deeper-bodied than males, while males tend to be more slender.

These omnivorous rasboras thrive on a varied diet of high-quality micro pellets and finely crushed flakes, supplemented with small frozen or live foods such as daphnia, baby brine shrimp, cyclops and mosquito larvae. Feed small portions that they can finish quickly, as their small mouths and active lifestyle are best suited to little and often feeding. Occasional live foods can improve colour, vitality and breeding condition.

Purple Harlequin Rasboras are excellent community fish and can be housed with other peaceful, similarly sized species. Suitable companions include small tetras, pencilfish, danios, other rasboras, Corydoras, small peaceful loaches, Otocinclus and dwarf gouramis. Avoid large, aggressive or predatory fish, fin-nippers and boisterous tankmates that may frighten them or outcompete them for food. They should not be kept with fish large enough to swallow them.

Purple Harlequin Rasboras are egg-scattering fish that breed most successfully in mature, dimly lit aquariums with soft, acidic water. Condition a group with plenty of small live or frozen foods, then provide broad-leaved plants such as Anubias or Cryptocoryne. A pair typically lays adhesive eggs on the underside of a leaf, after which the adults should be removed because they may eat the eggs. The eggs usually hatch in around 24 to 36 hours, and the tiny fry need infusoria-sized foods before they can accept newly hatched brine shrimp.

Females generally have a fuller, rounder abdomen and a deeper body, especially when mature or carrying eggs. Males are usually slimmer and may show a more sharply defined black wedge, with the lower front edge of the marking appearing more pointed than in females.