Rasbora Wedge-Spotted – a Fish with a Black Triangle

The wedge-spotted rasbora is one of those fish that is able to “revive” the aquarium, being in constant motion. Why else aquarists around the world fell in love with this small nondescript fish, you will learn from our article.

General information

Rasbora heteromorph (Trigonostigma Heteromorpha), or wedge-spotted rasbora (wedge-shaped) is one of the most popular fish, which is found in almost every pet store. Aquarists loved her for her small size, unpretentious content, unusual body color, and pleasant “fussiness”.


The cuneiform rasbora is a small fish, its size in the aquarium rarely exceeds 4 cm. The body is high, compressed from the sides, the caudal stem is thin. The pectoral and pelvic fins are pink, the back and caudal fins are red. The back is olive green, the abdomen is silvery. A characteristic feature is a large black wedge-shaped spot that runs from the tail to the middle of the body. By the shape of this spot, you can easily determine the gender


In the nature of rasbora, cuneiform inhabits water bodies of Southeast Asia: Thailand, Singapore, Borneo, Sumatra, Malaysia.

Prefers rivers and streams flowing under the canopy of dense jungle. Due to the large litter and decomposition of roots, the water becomes soft and acidic, acquires a rich “tea shade”.

Fish first came to Russia in 1911.

Care and maintenance

To keep the wedge-spotted rasbora, an aquarium with a volume of 40 liters or more is required. The fish is schooling, so the number of individuals should be at least 6-7. It is best to use dark soil and dense thickets of plants as decorations, which will allow the fish to hide if necessary. It would be useful to add natural driftwood, which will release tannins into the water, creating an environment close to nature.

Filtration should not be very powerful, fish do not like strong currents in the aquarium. Dimmed light is recommended, as bright lighting causes stress in the fish and, often, fading of color.

Optimum water parameters for the content: T = 23-28 ° C, pH = 6.5-7.8, GH = 2-12. Rasbora cuneiform prefers soft and acidic water, but due to its high adaptive abilities, it lives well in aquariums with higher rigidity. However, for dilution, the water will have to be softened. Weekly it is necessary to replace up to 25% of the water with fresh water.

The wedge-spotted tank should be densely planted with plants. The best option would be species that grow in reservoirs in the historical homeland of fish, for example, Cryptocorynes or Aponogetons, although any others will do. It is advisable to place floating plants on the surface of the water: hornwort, pistia, riccia.

The wedge-spotted rasbora prefers to stay in the upper and middle layers of water. Life expectancy up to 3-4 years.


The cuneiform rasbora is one of the most peaceful fish. She gets along well with almost all calm views. Other rasbora, tetras, neons, viviparous, scalars, catfish corridors, and ancistrus will become good neighbors.

Do not keep rasbora with fish that are very different in size. Despite their activity, they can fall prey to larger fish. And in no case should you add them to large and predatory cichlids, because sooner or later the rasboras will become live food for them.

Feeding rasbora

In nature, wedge-spotted rasbora feeds on worms, insect larvae, and zooplankton. When keeping in an aquarium, it must be borne in mind that the fish has a small mouth, so the food should not be very large. Rasbora prefers to eat near the water surface.

Tetra has launched the Tetra Micro Food line of dry food for small mouths especially for feeding fish with small mouths. You can choose any of four shapes: chips, sticks, pellets, or granules. The food is perfectly eaten by the fish and, thanks to the carefully selected composition, is maximally absorbed, which reduces water pollution.

TetraMin Basic Dry Flakes are also great for razor feeding. Flakes float on the surface for a long time, after which they gradually sink to the bottom. Fish can catch food both on the surface and in the water column.

For races with a predominance of red and orange shades in the color, it is recommended to feed with natural color enhancers, for example, TetraPro Color. These chips are made using a gentle low-temperature technology that allows you to preserve even more nutrients and vitamins in the feed.

Several times a week, you can offer your fish natural treats in Tetra FreshDelica nourishing jelly. Bloodworms, brine shrimp, krill, or daphnia will please your pets.

It is necessary to feed the fish with a small portion of food, which should be eaten in 2-3 minutes. Do not overfeed your fish or leave a lot of food in the aquarium.

Reproduction and breeding

Puberty in wedge-spotted rasbora occurs at the age of 9-12 months. You can distinguish between a female and a male by the shape of the body and a black spot in the form of a wedge. Males are brighter in color, and females have a rounder belly. Wedge in males is sharper and thinner, in females – rounded.

Breeding is very difficult, primarily due to the need for very soft water. Before spawning, producers must be planted and abundantly fed for a couple of weeks. A spawning aquarium should have a volume of at least 30 liters. It is advisable to plant Cryptocorynes or other plants with wide leaves in the spawning grounds. The water in the spawning area should be very soft, usually within 2-4 dGH, temperature – 26-28 ° C. The water level should not exceed 20 cm.

In the evening, a group of fish (2 males and 3-4 females) is planted in a prepared aquarium and left until morning. Spawning occurs with the first rays of the sun. First, mating dances of males follow, which stimulate the female to spawn. When the female is ready, she turns her belly upside down under a wide leaf of the plant and attaches the eggs to it. The male fertilizes them immediately. The process can take several hours, during which time the female lays up to 100 eggs, after which the parents must be removed from the aquarium.

The incubation period depends on the water temperature and can last 24-36 hours. The fry begins to swim on their own after a week. Starter feed – ciliates, brine shrimp nauplii, dry feed for fry.

Alice White

Written by Alice White

Alice White, a devoted pet lover and writer, has turned her boundless affection for animals into a fulfilling career. Originally dreaming of wildlife, her limited scientific background led her to specialize in animal literature. Now she happily spends her days researching and writing about various creatures, living her dream.

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