Rasbora espei is a popular and colorful fish in freshwater aquariums.
This species is known for being peaceful and looks great in community tanks with other small, friendly fish.
In this easy-to-follow care guide, we’ll explain how to take care of Rasbora espei, including what kind of tank they need, what to feed them, and what fish make good tank mates.
Whether you’re new to fishkeeping or have some experience, this guide will help you create the best home for these beautiful fish.
| Common name(s) | Lambchop rasbora, False harlequin |
| Binomial name | Trigonostigma espei |
| Care Level | Easy |
| Temperament | Peaceful |
| Size range – lenght | 1-1,2 inches |
| Water parameters | Temp 74-82°F (23–28°C) pH 6.5–7.0 Hardness 5-12 dGH |
| Tank level | Middle to top |
| Diet | Omnivore |
| Lifespan | 4-6 years |
| Breeding | Egg layer |
| Tank mates | Tetras (e.g., Neon Tetras, Cardinal Tetras), Danios, Corydoras Catfish, Peaceful Loaches, Shrimp (like Cherry Shrimp), Snails |
Origin
Rasbora espei originates from Southeast Asia. It is naturally found in slow-flowing freshwater streams and peat bogs in Thailand, Cambodia, and southern Vietnam.
It typically inhabits gently flowing sections of forest streams and tributaries, where submerged aquatic plants grow densely.
The water is sometimes lightly tinted brown or yellow due to the presence of tannins and other chemicals released by decaying organic matter and substrates covered with fallen leaves, twigs, and branches.
Such environments are characterized by soft, slightly acidic or neutral water, and they are often dimly lit due to dense riparian vegetation and tree canopies above.
Size
Rasbora espei is a small species, reaching adult sizes of about 2.5 to 3 cm (around 1 to 1.2 inches).
Their small size makes them a popular choice for nano tanks and planted aquariums, where space is limited, but active schools of fish are desired.
In the USA, a single Rasbora espei typically costs between $3.75 and $4.99. In Europe, prices generally range from €1.50 to €4.99 per fish. Prices may vary depending on factors such as the size of the fish, its breeding origin (wild-caught or farm-raised), and shipping costs.
Availability
Rasbora espei is readily available in most pet stores and online fish retailers.
They are often sold in groups because they are schooling fish and should be kept in groups of at least six or more to thrive.
Their relatively hardy nature and striking appearance make them a popular choice for aquarists of all experience levels.
Appearance and Sex Differences
Rasbora espei resembles the Harlequin Rasbora. The similarity is due to the wedge-shaped spot on its side. However, in “espei,” this spot is much narrower. Their bodies are notably slimmer and less arched. Their scales feature a distinctive, beautiful orange hue.
Compared to closely related species, such as the Harlequin Rasbora (Trigonostigma heteromorpha), the black markings of Rasbora espei are usually thinner and sharper.
Sexual dimorphism is subtle but noticeable upon closer observation. Females tend to have slightly rounder and deeper bodies, especially when viewed from above or when they are gravid (carrying eggs).
Males are generally slimmer and may display more intense coloration during courtship.
Behavior
Rasbora espei are calm, very sociable fish. They prefer to live in large groups and display natural schooling behaviors, which not only make them feel safe but also enhance their vibrant coloring.
Keeping them in a proper group size not only reduces stress but also results in a more impressive, natural-looking display. Males will also show their best colors when competing for female attention.
They are active swimmers and are often seen moving gracefully in the middle and upper parts of the tank.
If kept in small groups, they may become shy or stressed, so maintaining the proper group size is crucial for their well-being.
Care
They are peaceful and sociable fish, incredibly active—constantly swimming and patrolling the middle and surface areas of the tank. They are excellent for community tanks.
It is best to keep a group of at least 6-8 fish. Just avoid keeping them with aggressive or excessively large species, as they could become a meal.
The tank should be moderately planted but not too brightly lit. They are well-suited for shade-tolerant species of mosses, where the females like to lay eggs on the underside of the leaves.
Adding tannins is also recommended. These fish also look great in natural aquariums, where their single-species school stands out beautifully against a green plant backdrop.
A more natural setup may include a soft, sandy substrate with roots and branches arranged to create shaded areas and caves.
Adding dried leaf litter (e.g., beech, oak, or ketapang almond leaves) will further enhance the natural look, while also promoting the growth of beneficial microbial colonies as the leaves decompose.
These microbes can serve as a secondary food source for the fry, while tannins and other chemicals released by the decomposing leaves help simulate blackwater conditions. The leaves can be left in the tank to decompose fully or removed and replaced every few weeks.
This species seems to do best in relatively low lighting, and plant species from the genera Microsorum, Taxiphyllum, Cryptocoryne, and Anubias are recommended as they will grow well under these conditions. Adding some floating plants to further diffuse the light can also be effective.
Regular partial water changes, monitoring water parameters, and providing a stress-free environment will help ensure their health and longevity.
Tank Requirements
Tank size: Minimum 10 gallons (preferably larger if keeping a larger group).
Water temperature: 23–28°C (74–82°F).
pH: 6.5–7.0.
Hardness: Soft to moderately hard water (up to 12 dGH).
Substrate: Fine gravel or sand with plenty of live plants.
Lighting: Moderate; subdued lighting highlights their natural colors.
Filtration: Gentle filtration to maintain water quality without creating strong currents.
Decor: Provide hiding spots with plants, wood, and leaf litter to replicate the natural peat bog environment.
Diseases
Rasbora espei are generally hardy, but like all aquarium fish, they can be susceptible to common freshwater diseases if stressed or kept in poor conditions.
Some potential issues include:
- Ich (white spot disease).
- Fin rot.
- Fungal infections.
- Bacterial infections.
Preventive measures, such as quarantining new fish, maintaining excellent water quality, and providing a stress-free environment, will greatly reduce the risk of diseases.
Tank Mates
This species is very peaceful, making it an ideal inhabitant for a well-maintained community tank.
Since they do not have extreme water chemistry requirements, they can be kept with many popular species in the hobby, including other small cyprinids, as well as tetras, livebearers, dwarf cichlids, catfish, and loaches.
As always, thorough research is essential when selecting compatible tankmates, and their small adult size must be considered.
Suitable tank mates include:
- Other small rasboras (e.g., Harlequin Rasbora, Chili Rasbora).
- Small tetras (e.g., Neon Tetras, Ember Tetras).
- Corydoras catfish.
- Otocinclus catfish.
- Dwarf gouramis (peaceful varieties).
- Shrimp and snails
Avoid keeping them with large or aggressive fish that may hunt or intimidate them.
Diet
Rasbora espei are omnivorous and accept a wide range of foods. In the wild, they feed on small insects, larvae, and zooplankton. In captivity, a balanced diet should include:
- High-quality flake or micro-pellet foods.
- Frozen or live foods such as brine shrimp, daphnia, and mosquito larvae.
- Occasional feeding of finely chopped vegetables or algae-based foods.
In the aquarium, their feeding is not difficult—they will eat any type of live, frozen, or dry food sized appropriately for their small mouths. Particularly valuable foods are copepods, daphnia, and midge larvae.
Feeding small amounts two or three times a day helps keep the fish healthy and active.
Breeding
Successful breeding and raising Rasbora espei fry is not easy and presents a challenge even for experienced aquarists.
Two weeks before the planned spawning, males and females should be kept separately. During this time, they should be well-fed, ideally with brine shrimp larvae.
Simultaneously, prepare the breeding tank. You can omit substrate, placing only a small bush or a clump of thoroughly cleaned small mosses in the center of the tank (some breeders also place boiled peat at the bottom).
Introduce the separated pair of fish into the prepared tank. Some breeders recommend selecting an older male and a young female.
Increasing the temperature and adding more tannins to the water simulates the approach of the breeding season and stimulates the fish to spawn.
Usually, spawning occurs within 24 hours. At the peak of the courtship dance, the fish approach the moss.
The female turns upside down and begins laying eggs, attaching them in batches of 3-5 to the underside of the leaves.
During this time, the male, lying on its side, wraps its body around the base of her caudal fin and fertilizes the eggs. Once spawning is finished, remove the adult fish immediately.
A few drops of tripaflavin can be added to the water, and the tank is best dimmed.
The young (usually in the dozens) will hatch within 24-36 hours and remain suspended on the plant leaves.
In the early days of life, they will feed on the yolk sac. After five days, they begin foraging. It is best to provide them with live protozoa.
In Conclusion
Rasbora espei is a beautiful addition to any freshwater aquarium.
Their striking coloration, peaceful temperament, and schooling behavior make them favorites among aquarists.
With proper care, the right environment, and attention to their social needs, these charming fish can live up to five years in captivity, providing lively activity and natural beauty to your aquarium.
Whether you’re a beginner or an experienced hobbyist, Rasbora espei will undoubtedly be a delightful and rewarding species to keep.
