Chinese Hillstream Loach
Pseudogastromyzon myersi
Gastromyzontidae
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About
Pseudogastromyzon myersi is the flat, sucker-bellied loach sold as a Chinese hillstream loach, Chinese butterfly plec or Hong Kong otocinclus, and every one of those labels sets up the same purchase: an algae eater for a warm, still community tank. It is neither an algae eater nor a warm-still-water fish. It comes from fast, clear creeks in Guangdong and Hong Kong, and Seriously Fish recommends 18.9-23.9 °C, adding that it can withstand warmer conditions only "provided dissolved oxygen levels are maintained" - warm plus still is precisely the combination it cannot survive, because oxygen falls exactly where a tropical community tank sits. Turnover should be above ten times per hour, with powerheads or airstones if the filter cannot manage it. The food half of the mismatch is quieter and kills more slowly. Seriously Fish calls it a specialised biofilm grazer feeding chiefly on filamentous Cyanobacteria and stalked diatoms plus micro-invertebrates, and asks for regular live or frozen Daphnia, Artemia and bloodworm - so the soft green algae people buy it to clear is largely not what it eats, and a clean tank starves it over months. It also notes plainly that "although sometimes sold as such this species makes a poor companion for goldfish". It reaches about 6 cm, wants a base of at least 75 x 30 cm, a tight lid because it climbs glass, and a group of six or more; it is peaceable with most fish, and Seriously Fish actually recommends the larger, more robust hillstream genera - Beaufortia, Sewellia, Sinogastromyzon - as tankmates, while warning that smaller, less dominant Gastromyzon and Hypergastromyzon can suffer excessive harassment from it.
Care
Cool, fast, oxygen-saturated water: 20-23 °C, turnover above 10x per hour, extra powerheads or airstones, and smooth algae-covered stones under strong light. Tight lid - it climbs glass. Keep six or more, and feed frozen Daphnia, Artemia and bloodworm as well as biofilm: it is not an algae crew, and a clean tank starves it slowly. A poor tankmate for goldfish, and for smaller flat-bodied loaches such as Gastromyzon and Hypergastromyzon, which it harasses - but larger, more robust balitorids (Beaufortia, Sewellia, Sinogastromyzon) are the ones Seriously Fish recommends.
Diet
Specialised biofilm grazer taking filamentous cyanobacteria, stalked diatoms and small invertebrates. Supplement with live or frozen Daphnia, Artemia and bloodworm; a mature, algae-grown hardscape is what actually keeps it fed.
Tankmate compatibility
Gets along with (94)
Possible with care (236)
Avoid (88)
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.
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Frequently asked questions
- What tank size does a Chinese Hillstream Loach need?
- A Chinese Hillstream Loach needs an aquarium of at least 80 litres (21.1 US gallons) with a footprint at least 75 cm (29.5 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Chinese Hillstream Loach need?
- Chinese Hillstream Loach does best at 18–24 °C (64.4–75.2 °F), pH 6–7.5 and a general hardness of 1–12 °dGH.
- What group size does a Chinese Hillstream Loach need?
- Chinese Hillstream Loach is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.
- Is the Chinese Hillstream Loach suitable for beginners?
- Chinese Hillstream Loach is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.