Rosy Loach
Petruichthys sp. 'rosy'
Nemacheilidae
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About
The rosy loach is a genuinely nano loach from Shan State in Myanmar - Seriously Fish gives a maximum standard length of 25-30 mm - and it has never had a valid scientific name. It arrived in the hobby under the invented binomial "Tuberoschistura arakanensis", was traded for years as Yunnanilus sp. 'rosy', and now sits in Petruichthys following Kottelat's 2012 catalogue, still formally undescribed. Seriously Fish files it as Petruichthys sp. 'rosy' and lists Yunnanilus sp. 'rosy', Yunnanilus sp. 'orange', Tuberoschistura arakanensis and 'Burmese pink loach' alongside it. Shops print all of them, and every one is this fish. Do not confuse it with Yunnanilus cruciatus, which is a different, formally described Vietnamese species now called Micronemacheilus cruciatus. Its problem in a community tank is scale. At 2.5 cm it is bought as an undemanding nano fish, but it is a micropredator that wants small live and frozen foods, and it loses every race for food against anything larger or faster. Seriously Fish calls it "peaceful and surprisingly bold for its size" and asks for "at least 8-10 specimens, ideally more": in a proper group in a quiet, densely planted tank it stays out in open water, and males take on a brighter orange as they come into breeding condition. In a mixed community with barbs or danios it is a fish you paid for and never see.
Care
Tiny - 2.5-3 cm - so plan the tankmates, not the tank: 8-10 or more in a quiet, densely planted 60 x 30 cm tank at 23-25 °C with gentle flow and neutral to slightly alkaline water. Feed small live and frozen foods; flake and pellets are too large for its mouth. Nothing fast or large as company, or it will be out-competed at every feeding.
Diet
Micropredator. Live or frozen Daphnia, Moina and Artemia nauplii, plus very finely crushed dried food. Standard flake and pellets are too big for a 25-30 mm fish.
Tankmate compatibility
Gets along with (182)
Possible with care (154)
Avoid (82)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
What works for this species, most reliable first.
- Adult sizeA hint only · only across animals of the same age
In many cichlids, catfish and loaches one sex simply grows larger — usually the male, though there are well-known reversals.
Also in these lists
Similar species
Same category and the closest water parameters — if this species isn't quite it, start here.
Health
Disease guide entries relevant to this species — worth a read before you reach for medicine.
The full disease guide →Sold in Lithuania
These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.
These links are unpaid: we get nothing for them and ask for nothing.
Frequently asked questions
- What tank size does a Rosy Loach need?
- A Rosy Loach needs an aquarium of at least 45 litres (11.9 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Rosy Loach need?
- Rosy Loach does best at 20–26 °C (68–78.8 °F), pH 6.5–8 and a general hardness of 5–15 °dGH.
- What group size does a Rosy Loach need?
- Rosy Loach is a social species — keep a group of at least 8 so natural behaviour emerges and stress stays low.
- Is the Rosy Loach suitable for beginners?
- Rosy Loach sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.