Introduction Harlequin Rasbora

The harlequin rasbora (Trigonostigma heteromorpha) is a popular aquarium fish which belongs to the family Cyprinidae under Order Cypriniformes of Class Actinopterygii. This fish species is a native to Malaysia, Singapore, Sumatra and southern Thailand. It inhibits streams and other water bodies that are located in peat swamp forests. They are typical black water fish that prefers soft and acidic water.

Harlequin Rasbora’s Overview

The harlequin rasbora has lozenge-shaped body with deeply forked caudal fin. The body has variable in color which can range from a pale pink or bright red to a copper orange along the top and bottom with a noticeably blue tint.  The posterior half of the body bears a large, roughly triangular black marking which tapers toward the terminal end of the caudal peduncle. The pectoral fins are situated immediately posterior to the operculum or gill cover while the pelvic fins are located along the ventral portion of the body. The dorsal, anal, caudal and pelvic fins have tint red color with red color concentration in the outermost rays. They swim in schools and are known as micro-predators which mainly feeds on small insects, worms, crustaceans and zooplankton. It grows up to 5 cm in length and can live up to 6 years.

Scientific Name: Trigonostigma heteromorpha

English Name: Red Rasbora, Harlequin

Origin: South East Asia

Adult Size: Up to 2 inches (5 cm)

Behavior: Peaceful

Tank Level: All regions of the tank

Minimum Tank Size:  2O gallons

Diet: Omnivore

Breeding: Egg layer – difficult to breed

Care level: Intermediate

Water pH: 5.5-8.0

Water Hardness: up to 12 dGH

Water Temperature: 73.0 to 82.0° F

Water Movement: Moderate

Lighting: Moderate – normal lighting

Lifespan:  5-6 years

Background of Harlequin Rasbora

The Harlequin Rasbora was first described by Duncker in 1904. It is distributed in Southeast Asia on the Malay Peninsula throughout western Malaysia, southern Thailand and Singapore. It is also known to occur on the island of Bintan in Riau Island province, Sumatra. It is also known as Red Rasbora, Harlequin Fish and Harlequin. It is sometimes called Black Harlequin Rasbora, Blue Harlequin Rasbora and Gold Harlequin Rasbora due to their color variations.

Housing Harlequin Rasbora

The Harlequin Rasbora is an adaptable fish in the aquarium due to their hardy and tough body. It is a shoaling fish that should be kept with at least own six individuals or more. It is peaceful aquarium fish that also should be kept with other similarly sized fishes including small characins, assorted small barbs, danios, other small rasboras, Corydoras catfishes, Otocinclus catfishes and others. It requires at least 20 gallons tank with good water quality. Water pH should be ranged from 5.5-8.0 while water hardness that should be varied between zero to 12 dGH. The water temperature should be maintained between 73.0 to 82.0° F. It is a black water species that prefers filtered water through peats.

The Harlequin rasbora prefers dimmed light and a few floating plants such as Cryptocoryne and Aponogeton species on the surface in the open area. At least 25 – 50% of the tank water should be replaced once a month. If the tank is densely stocked 20-25% should be replaced weekly or every other week. A dark bottom substrate is recommended. The substrate should also be vacuumed during water changes to avoid accumulation of waste.

Breeding Harlequin Rasbora

The Harlequin rasbora is a hard species to breed. The water hardness should not be higher than 1.5 to 2.5 dH during breeding time. The pH-value can be kept around 6.0 and the temperature should be around 82.4°F. The breeding aquarium for the harlequin rasbora requires the presence of suitable plants such as Cryptocoryne species. The water in the breeding aquarium must be soft and acidic. The parent fish should be conditioned heavily with live foods such as Daphnia and mosquito larvae. Spawning usually occurs in the morning hours. After spawning, the parent fishes should be removed from the breeding aquarium to prevent eating eggs which may occur with this species.

The harlequin rasbora is not an egg-scatterer which deposits its eggs on the underside of a broad leaf of aquatic plants. The female lays up to 300 eggs which hatch after 18-36 hours and the offspring becomes free swimming 3-5 days after. The fry are 3 to 4 millimetres long and it should be fed with infusorians or other small food. If infusoria are unavailable, commercial prepared foods for egg layer fry may also be used. The hatchlings accept newly hatched brine shrimp after 7-14 days. The fry grows rather quickly and it looks like adult after 8 to 10 weeks.

Feeding Harlequin Rasbora

The Harlequin Rasboras is omnivores and in the wild condition it feeds on small insects, worms, crustaceans and zooplankton.  In captive condition it is easy to feed and usually accepts most food types. It should be given a balance of prepared quality flake or pellet food which should be supplemented with live snack like brine shrimp or bloodworms. Diet should be offered 2-3 times a day.

Sexing Harlequin Rasbora

The Harlequin rasbora is hard to sex. The female has usually a little bit larger and rounded body while the male is usually smaller and more slender with more brightly colored.

Harlequin Rasbora for sale & Where to buy

The Harlequin rasbora is a common and popular aquarium fish that can be found in most well stocked fish stores and it is generally inexpensive. They are found in a variety of color patterns in pet stores such as Black Harlequin Rasbora, Gold Harlequin Rasbora and Blue Harlequin Rasbora. To buy your harlequin, look below online vendors where to buy Harlequin Rasbora.