Species Snapshot
- Species Name: Trigonostigma espei
- Common Names: Lambchop rasbora, espei rasbora
- Size: Up to 1.5 inches
- Lifespan: 4-6 years
- Native Distribution: Thailand and Cambodia
If you think the lambchop rasbora looks familiar, you’re not wrong. Easily identified by the black, lambchop-shaped marking on its side, this species is often confused with the harlequin rasbora. In this guide, you’ll learn how to tell the difference and everything you need to know to care for lambchop rasboras properly.
What Do They Look Like?
Members of the genus Trigonostigma, lambchop rasboras (Trigonostigma espei) are small, ray-finned fish primarily found in Thailand and Cambodia. Lambchop rasboras are bright copper red in color with a light underbelly and translucent fins.
The most identifiable feature this species has is the black marking on its side that looks similar to the shape of a lambchop. The widest part of the marking sits around the center of the fish’s body and ends just before the caudal fin. Some fish exhibit an even more vibrant red color directly under the marking that fades into the lighter-colored belly.
How Big Do They Get?
Like most rasboras, lambchop rasboras remain fairly small. They are sometimes considered dwarf rasboras because they only reach an average length of 1 to 1.5 inches at maturity. Most rasbora species top out between 3-4 inches, though the porthole rasbora (Rasbora cephalotaenia) has been known to achieve 5 inches of length.
Lambchop vs. Harlequin Rasbora
Looking at the lambchop rasbora, it’s easy to confuse it with the harlequin rasbora (Trigonostigma heteromorpha). These two species are similar in size with the same copper red coloration and noticeable black marking. The differences between the two species are subtle but noticeable if you know what to look for.
Compared to the lambchop rasbora, harlequin rasboras have a slightly pinkish hue. Side by side, the lambchop-shaped marking on the harlequin rasbora is broader, darker, and more triangular in shape. In the body, harlequin rasboras have a deeper body shape as well.
Because these two species look so similar, the lambchop rasbora is sometimes called the false harlequin rasbora. True harlequin rasboras get just a little bit larger, however, while lambchop rasboras have a slimmer profile overall.
Lambchop Rasbora Care Guide
With their peaceful temperaments and hardy adaptability, lambchop rasboras are a popular pick among freshwater aquarium hobbyists. They’re relatively undemanding and generally do well in a properly maintained tank with peaceful tankmates and at least five or six others of their kind.
Let’s dive into the details of lambchop rasbora care.
Tank Size and Décor
While lambchop rasboras stay pretty small, they’re best kept in groups with at least six of their own kind. The minimum recommended tank size for a small group of these rasboras is 10 gallons, though a 20-gallon tank is much preferred. The larger the group of rasboras (and the number of other fish you’re keeping), the bigger the tank should be.
Like their cousin, the harlequin rasbora, lambchop rasboras do very well in planted tanks. They enjoy swimming amongst the plants and their red coloration stands out against the green. If you really want to make their color pop, choose a dark substrate and incorporate other natural décor elements like driftwood and rockwork.
One thing to keep in mind is that lambchop rasboras tend to prefer dim lighting. If you’re going to cultivate a planted tank, stick with low-light varieties like Anubias, Cryptocoryne, and Taxiphyllum. Another option is to add some floating plants on the surface of the tank to help diffuse the lighting.
Water Parameters
In their native habitat, lambchop rasboras inhabit gently flowing streams and tributaries. They prefer clean water, though some staining from driftwood and leaf litter isn’t unwelcome. What’s most important is the temperature and water chemistry profile.
As a tropical species, lambchop rasboras prefer warm water in the 74°F-82°F range. Soft, slightly acidic to neutral water is preferred, so aim for a pH between 6.5 and 7.5. Water hardness should ideally be kept under 12 dGH.
Lambchop rasboras are fairly hardy but they require a clean, well-maintained tank like any other species. Make sure your tank is fully cycled before adding your fish and always treat tap water with dechlorinator when performing water changes. Your tank should also be equipped with a heater to maintain stable temperature and a filter to facilitate both mechanical and biological filtration.
Feeding Tips
In the wild, lambchop rasboras are micropredators. They feed on very small insects and crustaceans as well as zooplankton. Tank-bred specimens usually accept a broad range of commercial foods, as long as they are small enough. Finely crushed flakes, micropellets, or granules are ideal as a staple diet. Supplement the diet with small life, frozen, or freeze-dried foods like brine shrimp, microworms, or daphnia.
Tank Mates
It’s important to keep lambchop rasboras in groups with at least six of their own kind but, other than that, they’re pretty flexible. The key is to avoid any large, predatory fish that might feed on them and stick to peaceful community fish.
Lambchop rasboras can easily be mixed with other rasboras as well as other small freshwater fish like tetras and livebearers. Docile bottom-feeders like Corydoras catfish and loaches make good tank mates as well.
Breeding Lambchop Rasboras
In ideal conditions, lambchop rasboras may breed on their own but starting with a group of 8-10 is the best way to ensure you’ll have a good mix of males and females. Sexing can be tricky and may only be possible when the fish mature. Females tend to be a little slimmer than males but larger in body while males often have a sharper, more defined outline in the wedge-shaped marking along their side.
Unlike other small cyprinids, lambchop rasboras attach their eggs to the underside of broad-leafed plants instead of scattering them. After spawning, the fish won’t exhibit any parental care, so consider setting up a separate breeding tank so you can remove the adults after spawning. Once the eggs hatch, you’ll need to offer small amounts of very small foods to help the fry develop.
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