Chinese Algae Eater

The Chinese algae eater is the best-known member of its own family (Gyrinocheilidae). Despite its name, its main range is Thailand, Laos, Cambodia and Vietnam. Its mouth works like a suction cup; while clinging to surfaces, the fish can breathe by taking in water through a small extra opening above the gill cover.

It is sold in stores as 4–5 cm juveniles under the label "algae cleaner". It does this job well when young; but it reaches 20–25 cm as an adult, loses interest in algae and becomes grumpy. The golden-yellow form is very common in the trade.

• Golden (golden algae eater): a form with a yellow–gold body and no pattern or a very faint one; its behavior is the same as the wild form.

It lives in flowing rivers and streams of the Mekong, Chao Phraya and Mae Klong basins, on bottoms full of rocks, roots and submerged branches. In strong current it holds on to surfaces with its mouth.

• Volume: at least 250 liters and 120 cm of length for one adult.
• Water: 24–27°C; clean, oxygen-rich water and moderate current.
• Decor: rocks, roots and caves; wide surfaces it can graze.
• Lid: a tight lid is recommended.

When young it feeds mainly on algae and biofilm. Adults are omnivorous and want more protein: sinking tablets and granules, spirulina, blanched vegetables, frozen bloodworms and brine shrimp. A well-fed individual turns on other fish less often.

Peaceful when young. As it matures it sets up a territory and chases its own kind and similar bottom dwellers. Its best-known problem is latching onto the bodies of slow, flat-bodied fish such as discus, angelfish, gouramis and goldfish and rasping off their slime coat; this leads to wounds and infection.

Good companions: fast-swimming medium to large schooling fish (barbs, large danios, rainbowfish), robust medium-sized cichlids.

Avoid: discus, angelfish, gouramis, goldfish and other slow, flat-bodied species; a second Chinese algae eater; peaceful small bottom dwellers.

Keeping it alone is recommended. Several individuals can live together only in very large, divided aquariums with enough territories and hiding places; otherwise they fight constantly.

Breeding in the home aquarium is not known. Commercial breeding is done on farms with hormone support.

Hardy. It is sensitive to sudden water changes and low oxygen. In an adult, insufficient protein can increase the tendency to go after other fish. Fish whose slime coat has been rasped show pale, whitish patches and wounds on the body; in that case the Chinese algae eater should be removed immediately and the injured fish monitored for infection.

Hard to tell apart externally. In mature males, small bumps (breeding tubercles) may appear around the snout during the breeding season; females are plumper.