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Main Index > Detailed Fish Profiles > Cyprinids > Harlequin Rasbora
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Trigonostigma (Rasbora) heteromorpha


    A beautiful and peaceful schooling fish, the Harlequin Rasbora will make a great addition to any community tank. Its' Coppery color catches the light and provides a stunning display.

Quick stats:

    Listed tank sizes are the minimum
    Size: 1 3/4 inches (5cm)
    Tank: 20 inches
    Strata: Top, middle
    PH: 5 to 7
    Hardness: Soft to medium
    Temperature: 73° to 82° f (22 to 25°C)


    Order: Cypriniformes
    Suborder: Cyprindei
    Family: Cyprindae
    Genera: Trigonostigma


Common name:

    Harlequin Rasbora, Red Rasbora, and Harlequin

Image gallery:
    Additional species photographs


    Badmans' Forum


    Thailand, Eastern Sumatra and the Malay Peninsula

General Body Form:
    Different from most other Rasbora species, the Harlequin is stocky and tall with a convex belly area. Males are more slender than the females. They can reach a length of around one and three quarter inches (4.5cms)

    Perhaps the most characteristic feature of this species is the triangular shaped, Blackish Blue marking, which begins wide in the center of the body and becomes narrower as it extends back to the start of the Caudal fin. In the females the lower front of the Triangle is often indistinct, while in the males it has a sharp edge that extends down toward the belly area. The dorsal fin is a Red color with a yellow tip. The upper and lower tips of the Caudal fin are a bright Red with the inside rays being a pale Yellow. The Base coloration of the body is a silver color and the sides range from a Pink all the way to a Copper color.

    All Rasbora species are peaceful and unaggressive and can be kept with fish of similar temperament. They are strong swimmers and in nature prefer to be in small schools. They like to stay in the upper areas of the aquarium. Your tank should provide plenty of open space for swimming as well as some dense plantings to serve as shelter. The water temperature should be kept around 76f. Rasboras prefer soft water and if possible you should use a peat filter bag in your filter, (Tetras will benefit also ) They will eat flake, frozen as well live food.

    Still, usually clear waters in Southeast Asia

    Many species of Rasbora will breed without too much difficulty, spawning freely in soft, neutral or slightly Acidic water. Unfortunately Rasbora Heteromorpha is not one of these. The water should be very soft with a hardness of 1.5 to 2.5 DH and a Ph of around 6.0. A long breeding tank is also beneficial with a dark substrate. The mating consists of the pair lying upside down under a leaf or similar with the male curling his tail around the female. It may take several days in the spawning tank before mating takes place. The parents will eat their own eggs so it is very important to remove them from the tank right away. After the parents are removed you should carefully lower the water to a depth of four or five inches. The eggs will hatch in 24 to 30 hours and in three to five days the fry become free swimming. The young should be fed on baby brine shrimp and other small foods. Growth is fairly rapid.


Your comments:


Please remember that the following comments are personal experiences and may or may not apply to your setup. Use them as guide to help better understand your fish, like us all individuals will behave differently under different circumstances.


From: David
I have a 20 gallon tank that contains 8 Harlequins. They are full grown at two inches in length. They are kept with 12 full grown zebra danios, a full grown red tailed black shark, two full grown butterflyfish, and a eight inch black ghost knifefish. The rasboras are very active and even school and play tag with my danios. I hope that the bgk will get used yo them and will not have them for dinner one night, but so far do good. My temperature is around 78 F, and my ph is 6.5. The fish are fed flakes, bloodworms, frozen brine shrimp, and live ghost shrimp. These are the perfect fish for any tank.
From: Richard
I have just acquired 9 of these fish in their juvenile stage around 1cm long. They are probably the most active fish I have encountered & are always shoaling & darting about. They are in a moderately planted 4ft (240L) tank with 4 juvenile Marble Angels. Simply stunning.
From: Andrew Givens
I currently keep 5 harlequins in a 16x8x8" clear-seal tank with algarde biofoam filter at 26c in soft, slightly acidic water. An arcadia original tropical lamp really highlights their colours! Dark sand and Java fern on small pieces of bogwood suits them well. Their tankmate is a male Betta splendens who is happy and confident in their company - the harlequins have made the betta more active and brazen! I've also kept them in a large mixed community - they've always done well in any tank, but keep them away from angelfish! They are rather disease-resistant, very adaptable and easy to feed. A great starter fish.
From: mllecathryn
These fish are excellent schoolers! They are so fun to watch in an aquarium since they swim together so well. Also, they are hardy, attractive, and get along well with other fish!
From: Jake
These are lovely, active rasboras. They do best in slightly acidic, soft water. Keep about 12 of these and you will have a glorious sight to behold.
From: Olie
I have eight of these and they seem to thrive on mosquito larvae, some kind of bugs that run across the water's surface, frozen foods and flakes. I also have guppies tetras and kribs and a new firemouth. There are corys , coolie loaches and some others which I can't name. They bred once but like what I said in the firemouth section, the large and very territorial kribensis male stopped them in the their tracks and the eggs soon rotted away.

From: Caz
Rasboras, are wonderful little fish, I have 8 in my tank, 2 have been with us for over a year now and the other 6 we have had for 8 months. They are so hardy, I had a serious bout of white spot a few months ago, half my fish died but all survived without a spot. I would recommend these fish to any community tank, they are lovely little fish.

From: anonymous
I just recently got 4 harlequin Rasboras and now I cant live without them! I got them because I knew they are very fast, high spirited fish. The first time I put them in my tank everything started moving around and got very active. They are such wonderful little fish!!!





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