Harlequin fish (Rasbora Heteromorpha)

Written by Robert Walker On October - 2 - 2011 under Fish Breeds 0 Comment

Of the 50 species of Rasbora, Harlequin is among the most popular fish. This is often called because of its color as a Red Rasbora is similar to that of copper, red, accented by a black line on the back.

Scientific name: Rasbora Heteromorpha
Other names: Red Rasbora
Family: Cyprinidae
Origin: Southeast Asia, Malaysia, Singapore, Sumatra, Thailand
Size at maturity: 4.5 cm
Life: 6 years
Diet: omnivorous, consuming most types of food
Breeding: lays eggs, hard mating
Care: Regular
water pH: 6.0-7.5
Water hardness: up to 12 DGH
Temperature: 23-28 degrees Celsius

Habitat / Care

Being freshwater fish, you will never find any Rasbora Heteromorpha in brackish water. They can be found in the waters south of the South-East Asia. Harlequin fish prefer an environment with dense vegetation, open areas for swimming, a dark substrate and discrete light.

Water temperature is very important. However, the ideal is located between 23 and 26 degrees C. The pH should be slightly acidic water, with the value between 6.0 and 6.5. Fish live in schools and should be kept in groups of at least 3 copies. They have no problems in tolerating other species of fish.

Not being demanding will accept food in any form: flakes, dry food, frozen or live. A varied diet will prevent digestive problems or diseases.


Finding themselves among the most difficult fish to reproduce; Harlequin fish can however, reproduce in appropriate circumstances. Young specimens should be selected and fed live food before reproduction. Males are slimmer than females and have a curved black stripe. Female black stripe is perfectly right.

Schools of young fish can be breaded in a single aquarium. For each female there must be two males. Water should have a pH value up to 2 DGH. Optimal water temperature is somewhere between 23-28 degrees Celsius, and the breeding aquarium must have leaved plants (like Cryptocorynes).

Once ready the breeding aquarium, the bank may be introduced for breeding in the evening. Reproduction will take place during the morning and will be initiated by “dancing” males against female. The female will head to a plant to deposit eggs. The male can push and rub his belly side against the female back to direct her towards the mating location.

When ready for breeding, the female will rub her belly on the underside of the leaf. The male will approach her and will fertilize the eggs as they are released. Fertilized eggs are on the back of the leaf. Within two hours about 100 eggs can be fertilized.

After mating, the bank should be removed from the breeding aquarium. Otherwise the fish will consume fishes as they hatch. Fishes should be fed according to their stage of development. They will reach sexual maturity in about 6-9 months.

Harlequin fish (Rasbora Heteromorpha) Pictures Gallery

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