Espe's Rasbora

Lambchop Rabora, False Harlequin, Narrow Wedge Harlequin

Family: Cyprinidae Espe's Rasbora, Trigonostigma espei, Lambchop RaboraTrigonostigma espeiPhoto © Animal-World: Courtesy Courtesy Barbara Roth

The Espe's Rasbaora is an adorable little cyprinid originating from overgrown jungle streams!

The Espe’s Rasbora Trigonostigma espei (previously Rasbora espei) is yet another amazing aquarium fish from South East Asia. It is a relative new comer, described by Meinken as recently as 1967. This fish is found throughout the eastern slopes of the Gulf of Thailand in the countries of Cambodia, Thailand, and more recently a population has been found from the Island Phu Quoc of Vietnam.

This is a small, agile cyprinid fish that only reaches about an inch (3 cm) in length. It has unique bronze color with a pink blush, which you really won’t find on any other aquarium fish. Its color can vary a bit depending on the locality it comes from, with some specimens having a more intense red. But its distinguishing feature is a black lambchop shaped marking on the side. Hence it is also popularly known as the Lambchop Rabora along with some other descriptive common names including False Harlequin, Narrow Wedge Harlequin, and Slim Harlequin.

Confusion with this fish runs rampant at times. It is often confused with two of its close relatives, the Harlequin Rasbora Trigonostigma heteromorpha and the Glowlight Rasbora Trigonostigma hengeli. The name 'Espe’s Rasbora' is also often mis-applied as the Hengel’s Rasbora. Both of these fish are frequently sold under the name of 'False Harlequin' as well.

To distinquish this fish from its conspecifics, notice some subtle distinctions. The Harlequin Rasbora is pale pink to bright red, and is much stocker than its cousins. The Harlequin’s black mark is also much closer to a triangle shape and will have a noticeably blue tint. The Glowlight Rasbora is more of a butter colored fish and will have an iridescent orange stripe above a thin and very rounded black triangle. The Espe’s Rasbora should be bronze pink in color and have no orange stripe above the black triangle.

This little rasbora is an agreeable fish that couldn’t be friendlier. It makes a great addition to any peaceful tank. They need to be kept in a groups of at least 8 - 10 individuals. Even though they have a tendency to not swim in a tight school, the companionship of their own species is absolutely essential.A school could be housed in a 10 gallon tank as the bare minimum, but a 20 gallon aquarium will suit them best.

They are very tolerant fish that require little extra care, so make great fish for the beginner. To bring out their best colors use a darker substrate and provide them with plenty of plants. The tank should be carefully covered as these fish are liable to jump if startled or excited. There simply isn’t a better fish to compliment a thoughtfully planted aquascape.

For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care


  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Cypriniformes
  • Family: Cyprinidae
  • Genus: Trigonostigma
  • Species: espei
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Espe's Rasbora - Quick Aquarium Care
  • Temperament: Peaceful
  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner
  • Diet Type: Omnivore
  • Minimum Tank Size: 10 gal (38 L)
  • Temperature: 73.0 to 80.0° F (22.8 to 26.7° C)
  • Range ph: 6.0-8.0
  • Hardness Range: 1 - 15 dGH
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Habitat: Distribution / Background

The Espe’s Rasbora Trigonostigma espei (previously Rasbora espei) was described by Meinken in 1967. It is found in South East Asia throughout the eastern slopes of the Gulf of Thailand in the countries of Cambodia, Thailand, and also a recent population found from the Island Phu Quoc of Vietnam.

This species is listed on the IUCN Red List as Least Concern (LC). Although there is some impact to the populations from trade it is considered stable. Other common names it is known by include Lambchop Rabora, False Harlequin, Narrow Wedge Harlequin, Slim Harlequin, Rasbora Espei, and Espei Rasbora.

There are currently four distinct members in the Trigonostigma genus. These fish were previously contained in the Rasbora genus but were reclassified in 1999 by Kottelat and Witte. They were distinguished by their triangular shaped pattern and coloring, as well as their reproductive method of depositing adhesive eggs underneath leaves or other matter rather than simply scattering them.

In nature this rasbora inhabits thickly vegetated streams, ponds, pools, marshes and swamps. These are peaceful waters that are calm or gently flowing. With the dense plant matter there is often decomposing organic debris, so the water is sometimes stained a yellowish brown by tannins and other chemicals. It is soft and weakly acidic or neutral, and the forest canopies often keep it heavily shaded. These fish swim in schools and are known as micropredators, feeding on small insects, worms, crustaceans and zooplankton.

  • Scientific Name: Trigonostigma espei
  • Social Grouping: Groups
  • IUCN Red List: LC - Least Concern

Description

The Espe’s Rasbora is a small slender fish, reaching a total length of just over 1 inch (3 cm). They have a typical lifespan of 3 to 5 years with good care. Their primary color is copper-orange, giving a pink blush appearance, and the body color appears to be increasingly reflective approaching the lateral line. It has a black lambchop shaped marking on the side and the fins are clear, except for yellow triangles on the dorsal fin and tail. Depending on the locality it comes from, some specimens are a more intense red.

  • Size of fish - inches: 1.2 inches (3.00 cm)
  • Lifespan: 3 years - They have an average lifespan of about 3 - 5 years with proper care.

Fish Keeping Difficulty

The Espe’s Rasbora is very hardy and makes a great fish for beginners. They are usually not very picky eaters. They will accept and thrive on quality flake foods. With well filtered water and regular maintenance these fish will do very well, but they must be kept in a school.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

The Espe’s Rasboras are omnivorous. In the wild they feed on small insects, worms, crustaceans, and zooplankton. In the aquarium their diet should be based around a quality flake or pellet food. This should be supplemented with the occasional live snack like brine shrimp or bloodworms. Some blanched lettuce or spinach is also a welcome addition to their diet. These fish will do best when offered food several times a day, but only offer what they can eat in 3 minutes or less at each feeding. If you feed only once per day, provide what they can eat in about 5 minutes.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day - Offer only what they can consume in 3 minutes or less with multiple feedings per day.

Aquarium Care

These fish are not exceptionally difficult to care for, they mostly just need their water to be kept clean. 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. The substrate should also be vacuumed during water changes to avoid accumulation of waste.

  • Water Changes: Monthly - It the tank is densely stocked the water changes should be done every other week.

Aquarium Setup

The Espe’s Rasbora is a hardy schooling species that will spend much of its time in the middle and upper regions of the aquarium. The tank should be no less than 18 inches (45 cm) long, so that these fish may comfortably school and swim back and forth. A school can be kept in a smaller 10 gallon aquarium, but will do best in about a 20 gallon size. Its colors can be quite stunning and will show best in soft, slightly acidic water conditions. Provide a good filter, but as these fish come from very sluggish waters, strong filtration is not necessary. The tank should be carefully covered as these fish are liable to jump if startled or excited.

A heavily planted tank will make them feel much more at home. A good aquascape would be dense plantings reaching the surface of the aquarium around the sides and back and a few broad leaved plants for shelter. A dark substrate and areas of shadow will bring out a much redder hue. Adding floating plants will give the fish extra security and help to diffuse the light entering the tank. Bogwood is also a great addition, as the tannins help maintain water parameters more closely to their natural environment. To create a natural feel and encourage the growth of microbe colonies add dried leaves to the tank. The microbe colonies will also act as a secondary food source.

  • Minimum Tank Size: 10 gal (38 L) - Though a school can be kept in a smaller aquarium, they will do best in about a 20 gallon size.
  • Suitable for Nano Tank: Yes
  • Substrate Type: Any
  • Lighting Needs: Moderate - normal lighting
  • Temperature: 73.0 to 80.0° F (22.8 to 26.7° C)
  • Breeding Temperature: 77.0° F - Breeding temperatures between 77 - 80° F (25 - 28° C).
  • Range ph: 6.0-8.0
  • Hardness Range: 1 - 15 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: All - Espe's Rasboras spend much of their time in the middle and upper region of the aquarium.

Social Behaviors

Espe's Rasbora Trigonostigma espei, Lambchop Rabora Espe's Rasbora, Lambchop Rabora Photo © Animal-World:
Courtesy Barbara Roth

These fish must absolutely be kept in groups of at least eight or more individuals. These rasboras are schooling fish by nature, but don't always swim in a tight school unless there are many individuals or there are other large fish in the tank. Nonetheless, these fish need to be kept in a group for their well being. You may notice some chasing in the school between fish, but injuries almost never result.The males will display their best colors as they compete for the attention of females.

They are generally peaceful fish with a disposition suited to the community aquarium. Yet they are active and so may disturb the peace of some less tolerant fish.

They can be kept with many popular community fish including other cyprinids as well as some of the characins like tetras, livebearers like mollies, guppies, platies, and swordtail fish. They also do well with bottom dwelling peaceful catfish and loaches, and even some of the dwarf cichlids. However they will suffer in the company of overly large and aggressive fish.

  • Temperament: Peaceful - They are peaceful fish but will get nervous with larger tank mates.
  • Compatible with:
    • Same species - conspecifics: Yes - This fish is only comfortable kept with a school of its own kind, they need to be in groups of at least 8 - 10 individuals.
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Threat - Because of their small size any aggressive fish are a threat.
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Slow Swimmers & Eaters (): Safe
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Safe

Sex: Sexual differences

The mature males are thinner and more brightly colored than the females. Females will have a higher body and fuller belly. The dark wedge-like markings on the male may also be have a sharper, more definitive outline.

Breeding / Reproduction

The Espe’s rasboras are moderately difficult to breed, though if kept in a well maintained aquarium with dense planting, you may see some young fish showing. Although like the other cyprinids they exhibit no parental care for the young, they differ slightly in their spawning method. Rather than being open water egg scatterers, their eggs are attached to the undersides of broad-leaved plants or other objects. In a controlled spawning, one or two pairs need be well conditioned with small offerings of live foods several times a day, usually for about 4 weeks. Conditioning well with live foods will also bring out the males color. When well fed, mature females should begin filling out with eggs.

It is best to provide a dimly lit breeding tank and keep the water level low, at about 6 - 8" (15 - 20 cm). The water should be very soft at about 2° dGH, slightly acidic with a pH of 5.3 - 5.7, and a temperature between 77 - 82.4° F (25 - 28° C). Filtration isn't really necessary, but you can add a small air-powered sponge filter or some peat filtration. They need either artificial or live broad-leaved plants, like Microsorium or Cryptocoryne, for the eggs to adhere too. A spawning mop can also be added so any eggs that don't attach to the leaves have a place to fall that's out of the reach of the parents.

Place one or two pairs in the breeding tank, and spawning will usually occur in the morning hours. The male will direct the female to his selected location, almost always the underside of a broad leaved plant. The male performs a courtship dance and the spawn takes place under the plant leaves, with the partners swimming upside down. After the spawn, remove the parents as they will eat the eggs and darken the tank. At this time lower the water level down to between 4 - 6 inches (10-15 cm), just make sure the eggs are below the surface.

The fry will hatch in about 24 hours and be free-swimming in about a 7 - 14 days. Feed the free swimming fry starter foods like infusoria for the first few days, until they are large enough to eat baby brine shrimp. See Fish Food for Fry for information about types of foods for raising the young.

  • Ease of Breeding: Moderate

Fish Diseases

Espe’s Rasboras are very hardy and disease is not usually a problem in a well maintained aquarium. If good water quality, nutrition, and maintenance is not provided, some diseases that are common in rasboras are dropsy, fin rot, and Ich. With any additions to a tank such as new fish, plants, substrates, and decorations there is a risk of introducing disease. It's advisable to properly clean or quarantine anything that you want add to an established tank prior to introduction, so as not to upset the balance.

These fish are very resilient but knowing the signs of illness, and catching and treating them early makes a huge difference. An outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. The best way to proactively prevent disease is to give your fish the proper environment and a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish will is more likely to acquire disease. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.

Availability

Espe’s Rasboras are also sold as False Harlequins or Lambchop Rasboras. They are somewhat difficult to find but a select few fish stores will carry them and they may be available online, and are fairly inexpensive.

References

Author: Barbara Roth, Clarice Brough CFS, Jeremy Roche
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