Chinese Hillstream Loach

The Chinese hillstream loach is the Pseudogastromyzon species most often found in the hobby. For years it was sold under the name P. cheni, but that species rarely enters the trade; fish whose dorsal fin has a yellow background and a red outer band are considered P. myersi. Adults grow to 5–6 cm.

With its flat body and broad fins, it clings to stones and can hold its position even in a current. Unlike other hillstream loaches, it breeds quite easily in the aquarium, which makes it a good starter species for those who want to set up a hillstream biotope.

It lives in mountain streams in the less developed areas of Hong Kong and the neighboring province of Guangdong. It is found in shallow, clear, fast-flowing, rocky water. Those in the trade mostly come from around Guangzhou.

• Volume: at least 70 liters and 75 cm in length for a group of 5–6.
• Flow and oxygen: strong flow and plenty of oxygen are essential; a circulation pump and an air stone in addition to the filter.
• Water: cool water at 19–24°C; it should not exceed 26°C in summer. pH 6.5–7.5. 30–50% water change weekly.
• Substrate: rounded fine gravel and sand; males dig nests, and the fry hide among the gravel.
• Decor: flat stones, rocks, plants attached to stones.
• Mature aquarium: biofilm should have formed on the stones.

It grazes biofilm, algae and diatoms on stones and also eats small invertebrates. Besides algae wafers and sinking dry food, frozen daphnia, brine shrimp and bloodworms should be given regularly.

Generally peaceful, but it can be harsh toward flat hillstream loaches that resemble it. Males are bolder and establish territories; dominant fish claim the best grazing spots.

Good companions: white cloud mountain minnow, zebra danio, small devarios and rasboras, small barbs that like flowing water.

Avoid: mixing it in a small aquarium with similarly shaped species such as butterfly loaches and Sewellia, goldfish, warm-water species.

At least 5–6 individuals are recommended. Males make mock attacks on each other and engage in short chases; if there are enough stones and shelters, no serious harm results. Females are more at ease in a group.

It has been bred in the aquarium many times. The male digs a shallow pit in the gravel or sand; the female lays her eggs in this nest and the male fertilizes them. There is no parental care. Depending on temperature, the eggs hatch in about 4–14 days. A mature gravel substrate is needed for the fry to hide; in the wild, spawning occurs in early summer.

• Oxygen: it is the first fish affected in hot weather and when the flow stops.
• Wasting: fish weakened after shipping recover in a mature aquarium with plenty of biofilm.
• Temperature: constant temperatures above 25°C damage its health.

Mature females are larger and fuller, with paler patterns. Mature males develop small bumps (tubercles) on the head; these are more prominent in dominant males.