Lambchop rasboras with shrimp

By the Shrimp Tank Hub editorsUpdated Oct 27, 2026Research-based

The lambchop rasbora, also called the copper harlequin or narrow wedge harlequin, is Trigonostigma espei, a small cyprinid from southwestern and southeastern Thailand and southwestern Cambodia, with a population also reported from Phu Quoc island in Vietnam (Seriously Fish, Maidenhead Aquatics). It looks like a smaller, coppery version of the harlequin rasbora with a thinner black body marking shaped like a lamb chop. Most populations live in gently flowing forest streams thick with submerged plants and soft, slightly acidic water, but Seriously Fish and Practical Fishkeeping note one population in limestone sinkhole pools in Krabi province, southern Thailand, at pH 7.0–7.4. The Shrimp Farm says lambchops and harlequins need the same care. For a smaller rasbora for nano tanks, see chili rasboras.

Lambchop rasbora at a glance

Will lambchop rasboras eat shrimp?

• Adult shrimp: usually safe. None of our sources tested lambchops with shrimp directly. The Shrimp Farm says harlequins are much too small to take an adult shrimp and that lambchops need the same care; lambchops are smaller still. Freshly molted shrimp are the most exposed (our reading).
• Shrimplets: some will be eaten. Seriously Fish describes wild lambchops as probable micropredators of small insects, worms, crustaceans and zooplankton, and Practical Fishkeeping lists rasboras among fish that will almost certainly eat young shrimp.
• Eggs and berried females: eggs are safe while carried under the tail.

Dense moss and plants let many babies survive (Aquarium Co-Op), so a cherry colony can keep growing, just more slowly than on its own. For similar choices, compare harlequin rasboras with shrimp, kubotai rasboras with shrimp and Boraras rasboras with shrimp, or see the full cherry shrimp tank mates list.

Matching the water

Seriously Fish lists 73–82 °F, pH 5.5–7.5 and 1–10 dGH. Maidenhead Aquatics gives 23–28 °C and pH 5.5–7.0 with KH up to 10, saying soft, slightly acidic water is best long-term. Practical Fishkeeping says the species' range across acidic streams and alkaline limestone pools suits it to a wide range of water. The Shrimp Farm lists 65–80 °F, pH 6.8–8.0 and GH 4–8 for cherry-type shrimp. By our comparison, the overlap is about 73–80 °F, pH 6.8–7.5 and GH 4–8, or pH 6.8–7.0 if you follow Maidenhead Aquatics; we'd aim for pH 6.8–7.2. See shrimp tank pH, GH and KH explained and shrimp tank temperature.

Tank size and setup

• Size: Seriously Fish says a base of 24 × 12 in is the smallest to consider, since the fish should be kept in numbers. Practical Fishkeeping still recommends the classic 2-foot tank used for harlequins.
• Dim, dense planting: Seriously Fish suggests a dark substrate, wood, leaf litter, fairly dim light and shade-tolerant plants such as Microsorum, Taxiphyllum, Cryptocoryne and Anubias, with some floating plants. Maidenhead Aquatics suggests dense planting among bogwood. Moss gives shrimp cover too. See java moss for shrimp and driftwood and botanicals for shrimp.
• Gentle flow: Maidenhead Aquatics says circulation and filtration should be gentle but efficient. A sponge filter or pre-filter keeps shrimplets out of the intake (our suggestion). See shrimp-safe filters.
• Start mature. See how to cycle a shrimp tank.

Group size and behavior

Seriously Fish says to keep at least 8 to 10, which makes them less nervous and brings out the males' colors; Maidenhead Aquatics says 10 or more. Practical Fishkeeping suggests a slightly bigger group than for harlequins, because the smaller fish can be less brave. Males are slimmer and more colorful, with a sharper-edged body wedge; females are rounder and often a little larger (Seriously Fish).

Lambchop or harlequin?

Both suit a shrimp tank in the same way. Lambchops are smaller, more copper-orange and have a thinner black wedge; harlequins reach about 1.8 in. The Shrimp Farm says the two have the same care and will school together. Maidenhead Aquatics notes the similar T. hengeli has much less color, with orange only around the wedge. See harlequin rasboras with shrimp.

Feeding both

Seriously Fish says lambchops are easy to feed but show the best color with regular small live and frozen foods such as bloodworm, Daphnia and Artemia alongside flakes and granules. Maidenhead Aquatics adds micropellets, baby brine shrimp and cyclops. Feed the fish first, then drop sinking shrimp food into a planted corner (our suggestion). See best shrimp food.

How to add lambchop rasboras to a shrimp tank

• Shrimp first. Practical Fishkeeping suggests letting the shrimp colony build up before adding fish; hiding places and well-fed fish reduce losses.
• Calm tankmates. Maidenhead Aquatics says large, active fish make them nervous. See otocinclus with shrimp and corydoras with shrimp.
• Acclimate slowly. See how to drip acclimate.
• Watch shrimp numbers for the first few weeks, especially after molts.
• Quarantine the fish separately. Practical Fishkeeping says many fish medications are not safe for invertebrates. If fish get sick, ask a fish veterinarian or an experienced store about treatment that won't harm the shrimp. See how to quarantine and is copper toxic to shrimp.

Common mistakes

• Keeping a handful in a bright, bare tank; Seriously Fish and Maidenhead Aquatics both point to dim light, plants and a bigger group.
• Letting leaf litter push the pH well below 6.8 in a tank with cherry shrimp.
• Mixing them with large, boisterous fish.
• Expecting every shrimplet to survive.

Track it

Log temperature, pH, GH and TDS on the free Water Parameter Log printable so you can keep the tank in the range both species share.

Frequently asked questions

Will lambchop rasboras eat cherry shrimp?

Not adults, in our reading: they are smaller than harlequins, which The Shrimp Farm says are too small for adult shrimp. They will eat some newly hatched shrimplets. We rate them a low to moderate risk.

What is the difference between a lambchop and a harlequin rasbora?

The lambchop (Trigonostigma espei) is smaller and more copper-colored, with a thinner black marking. The Shrimp Farm says care is the same and the two school together.

How big do lambchop rasboras get?

About 1.2 inches: 30 mm standard length per Seriously Fish or 3 cm per Maidenhead Aquatics; Practical Fishkeeping gives up to 4 cm.

What water do lambchop rasboras need?

Seriously Fish lists 73 to 82 °F, pH 5.5 to 7.5 and 1 to 10 dGH. With cherry shrimp, aim for about 74 to 78 °F and pH 6.8 to 7.2 in our reading.

How many lambchop rasboras should I keep?

At least 8 to 10 (Seriously Fish); Maidenhead Aquatics says 10 or more.

What size tank do lambchop rasboras need?

A base of at least 24 by 12 inches, about 14 US gallons (Seriously Fish), or a 2-foot tank (Practical Fishkeeping).

Sources: Seriously Fish, Trigonostigma espei (lambchop rasbora) (Trigonostigma espei; southwestern and southeastern Thailand, southwestern Cambodia, Phu Quoc; confused with T. heteromorpha and T. hengeli, copper to reddish with a thinner lambchop marking; gently flowing forest streams with dense plants; Krabi limestone pools pH 7.0–7.4; 30 mm SL; base 60 × 30 cm, about 54 L, 14 US gal; 23–28 °C, pH 5.5–7.5, 1–10 dGH; dark substrate, wood, leaf litter, dim light, Microsorum, Taxiphyllum, Cryptocoryne, Anubias, floating plants; probable micropredator of small insects, worms, crustaceans, zooplankton; bloodworm, Daphnia, Artemia, flakes, granules; very peaceful; groups of at least 8–10; males slimmer with sharper wedge, females rounder); Maidenhead Aquatics (fishkeeper.co.uk), Copper harlequin (copper harlequin, also sold as lambchop rasbora or narrow wedge harlequin; 3 cm; 23–28 °C; pH 5.5–7.0, KH up to 10, soft slightly acidic best long-term; groups of 10 or more; dense planting, bogwood, floating plants; gentle but efficient filtration; large, active fish make it nervous; T. hengeli has much less color; flake, micropellets, small frozen foods); Practical Fishkeeping, A guide to the small rasboras from the genus Trigonostigma (lambchop up to 4 cm; 2-foot tank; slightly larger group as smaller fish are less brave; acidic forest streams and alkaline limestone pools in Krabi; wide range of water); The Shrimp Farm, Harlequin rasbora care (lambchop rasbora a slightly smaller harlequin look-alike with a thinner marking; same care; school together; harlequins too small for adult shrimp); Practical Fishkeeping, What can I keep with shrimp? (rasboras will almost certainly eat young; let shrimp numbers build first; hiding places; well-fed fish; many medications unsafe for invertebrates); Aquarium Co-Op, Cherry shrimp tank mates (moss and plants for baby shrimp); The Shrimp Farm, Red rili shrimp tank set-up and care (cherry-type range 65–80 °F, pH 6.8–8.0, GH 4–8). Risk rating and the shared water range are our reading of these sources.