Chinese algae eater
Gyrinocheilus aymonieri
intermediate careOverview
The Chinese algae eater (Gyrinocheilus aymonieri) is one of the most over-sold fish in the hobby, and it’s important to be honest about it. It’s marketed as a cheap, hard-working algae cleaner — but it grows large, turns aggressive with age, and largely stops eating algae once mature. Plenty of keepers buy a small, busy juvenile and end up, a year later, with a 25 cm bully harassing the whole tank. For most community aquariums, there are far better choices.
Tank & water
If you do keep one, take its adult size and temperament seriously. A single fish needs a minimum of 200 litres (50 gallons) with a long footprint.
- One per tank: they are intolerant of their own kind and grow territorial, so keep only a single individual.
- Space and cover: open swimming room plus caves and wood to break up territory and give tankmates refuge.
- Water: pH 6.5–7.5, 22–27 °C on a reliable heater, clean and well-filtered by a strong filter.
- Mature tank: cycle fully before adding one.
Feeding
Despite the name, the adult is an omnivore that needs feeding, not left to “clean” the glass. Offer sinking algae wafers, quality pellets and flakes from the fish food range, blanched vegetables and occasional frozen foods. A concerning adult habit is rasping the slime coat off flat-bodied tankmates — another reason to reconsider keeping one.
Better alternatives
For most keepers this is the key section. Genuine, peaceful, lifelong algae control comes from:
- Otocinclus — tiny, peaceful, dedicated algae grazers for planted tanks.
- Bristlenose pleco — stays small, keeps eating algae and biofilm as an adult.
- Siamese algae eater — peaceful and one of the few fish that tackles hair algae.
- Nerite snails and amano shrimp for cleanup crews.
See our best algae eaters and do algae eaters really work answers before you buy.
Common mistakes to avoid
- Buying it as a permanent algae solution
- Keeping more than one
- Underestimating its adult size and aggression
- Housing it with flat-bodied fish it will rasp
Chinese algae eater — frequently asked questions
Do Chinese algae eaters actually eat algae?
Only when young. Juveniles graze some algae, but as they grow they lose interest and switch to prepared foods, protein and other fish's slime coat. An adult Chinese algae eater is a poor algae-eater — the name is misleading.
Why do Chinese algae eaters become aggressive?
It's simply how the species matures. They grow to 20–28 cm and become territorial and bullying with age, chasing tankmates and even latching onto the flanks of flat-bodied fish to rasp their slime coat. A peaceful juvenile can become a tank terror.
What should I use instead of a Chinese algae eater?
For genuine, peaceful, lifelong algae control choose otocinclus, a bristlenose pleco, nerite snails or amano shrimp. They stay small or peaceful, keep eating algae as adults, and won't outgrow or bully a community tank.
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