These fish are easily identified by their high, flattened laterally torso and a dark triangular spot, which gradually tapers in the back of the body and sets on the base of the caudal fin. The Latin name of the genus is translated as a triangular spot. The characteristic drawing served as a pretext for their English name – rasbory-harlequins.
Males, as a rule, have a brighter color. Representatives of this genus differ in reproduction biology.
Unlike the rest of the rasbor, during spawning they simply spread their eggs, the wedge-shaped glues the eggs to the lower surface of the leaves of aquatic plants.
This genus is widely distributed in the waters of South and Southeast Asia, in Indonesia and the Philippines. Representatives of the genus are mainly schooling fish, which stay in the upper layers of standing and slowly flowing water bodies.
Many species spawn in large groups.
Rasbor heteromorph or wedge-shaped (Trigonostigma heteromorpha)
A long-time favorite of home aquariums, the history of its content has more than a hundred years. For most aquarists, the name of the race is associated with this species, although, as we already know, it is the most atypical representative of this group. This is the largest (up to 5 cm) and the highest-heeled rasbor among all cynopathies.
Body color is pinkish, black wedge-shaped spot, starting from the middle of the body, wide, evenly tapering to the tail. In males, it is clearly delineated, in females – blurry, with a rounded lower top. In addition, males are distinguished by a brighter red dorsal fin.
The species is widely distributed in Thailand, Malaysia, Sumatra and Kalimantan.
Rasbora espei (Trigonostigma espei)
It differs from the previous species by a slightly smaller size with an elegant addition, a copper-red general tone of coloring, a thinner wedge of stain with a concave lower edge resembling a knife blade (in English this fish is called ‘lambchop rasbora’). Peaceful schooling fish for a common aquarium with shady areas.
Dense vegetation as shelters: broad-leaved plants and soft, slightly acidic peat water. There are two isolated populations of this species: one in the south-western part of Thailand, the other in the south-east of the country, on the border with Cambodia.
Coloring can vary considerably depending on the habitat.
Length: not more than 3.5 cm.
Water: temperature 23–28 С; PH is slightly acidic below 7; mild, dn 2-10.
Food: live, frozen and dry.
Area: Thailand, Cambodia.
Rasbor Hengel (Trigonostigma hengeli)
Rasbora Hengel very similar to the previous species, and they are often confused, although, if you look closely, these fish are very easy to distinguish. The overall color tone of this rasbor more pale, yellowish-gray, against the background of which burning orange spots are clearly visible, located in front of and above the dark triangle.
In general, it is slightly smaller than the races of Espay, the length of adults does not exceed 3.5 cm. The view is widespread in Sunda Islands – Sumatra and Kalimantan.
Rasbora somphongsi (Trigonostigma somphongsi)
The smallest member of the genus, reaching a length of only 3 cm, and at the same time characterized by the least high, progonistoy body. The spot only widens slightly in the anterior part and rather represents a longitudinal strip extending from the base of the tail to the middle part of the body.
Its front part is surrounded by bright yellow edging, but the overall tone is golden. The species is rare in nature and the details of its distribution need to be clarified.
Its dwelling in some western regions of Thailand is known for certain.
Wedge specks – schooling species, and if you keep them in an aquarium alone, they become nervous and fearful, moreover, all the splendor of color, especially in males, is manifested only in the presence of individuals of its own species. Being absolutely peaceful rasbora ideal for creating multi-species compositions in an aquarium with other peaceful fish of similar size.
Preparation of the reservoir for these rasbor does not require much trouble, the soil is desirable fine fraction, dark. In the dark colors it is desirable to withstand the background. As decoration, various snags, bamboo branches, etc. are appropriate.
It is advisable to fill the peripheral zone with dense thickets of water grasses. Illumination is diffuse, moderate, using a floating flora as a light filter.
The minimum volume of the aquarium – from 10 for a pair and 100 liters – for a group of 10-15 individuals.
Optimal conditions of maintenance: T = 23-28 ° C, dGH up to 12 °, pH 6.0-6.5, effective filtration, regular water changes of the same parameters up to 25% weekly. Fish are omnivores.
Breeding these fish process is extremely difficult. Fish maturity reaches 7-10 months, depending on the conditions of detention. Around this time they should be set aside for spawning.
In an optimal pair, the male should be one month older than the female. 10–12 days before spawning of producers (no more than 2 males and 3–4 females) need to be seated and fed abundantly, better – with bloodworms.
At the same time, the fish will get used to the water of a spawning fish, which is somewhat different in its parameters from the aquarium.
Spawning volume should be at least 30 liters. The presence of broadleaf plants, such as Thai fern or cryptocoryne, is required. Plants for spawning should be thoroughly cleaned, and the aquarium should be sanitized.
At the bottom to save the eggs is to put a grid. The spawning water level is not more than 20 cm. The water parameters in the spawning aquarium are as follows: hardness – 4, pH 5.5 – 6.5, temperature 26 – 28 ° C. Sharp drops are not allowed.
The spawning water should be filtered with peat extract or tetratorimine to the color of green tea. The lighting is preferably diffused.
However, sometimes spawns and in bright light.
If the conditions created in the spawning are favorable, the male begins to push the female down, circling over her. The female shortly thereafter will swim over the leaves of the plants, sometimes taking a vertical position upside down. Soon the male will join her.
He is wrapped around her body, after which the female lays several eggs, immediately sticking to the leaves. Everything is repeated many times. Some part of the eggs will still fall to the bottom of the aquarium, under the net.
In 1.5–2 hours of spawning, the female can sweep up to 300 eggs.
After spawning, the fish need to be transplanted back into the aquarium, and the walls of the spawn should be darkened. The larvae appear after 36 hours, and the fry are able to swim and feed already by the 5th day of life. As the starting feed, you need to use the smallest zooplankton: Artemia and daphnia.
Since the fry have excellent appetite, they need to be fed several times a day. Then you can add special dry food to their diet. Grown fry can feed on granulated fodders, coretica, enkhitreya, shallow bloodworms, cyclops, daphnia, artemia.
Grow fry rasbor very quickly.