Saturday Species Spotlight: The White Cloud Mountain Minnow, the Fish That Doesn’t Want Your Heater
Most small fish in the pet store want a heater. The white cloud mountain minnow (Tanichthys albonubes) usually doesn’t. In many heated homes, this little red-finned schooling fish does best with no heater at all. That makes it lovely in the right setup and quietly miserable in the wrong one.
Who he is
White clouds are tiny cyprinids, around 4 cm (about 1.6 in) fully grown, according to both FishBase and Seriously Fish. They come from clear, slow, planted streams in southern China and northern Vietnam. The species is named for White Cloud Mountain near Guangzhou, but appears to have vanished from the mountain itself. Between 1980 and 2001 it wasn’t recorded anywhere in the wild; a few relict populations have been found since.
Those wild fish turn out to be more complicated than one species. A 2020 genetic study of every known wild population found deep divergence between them, and the authors proposed seven cryptic species. China lists the minnow as a second-class state-protected animal. The IUCN’s only assessment, from 2010, lists it as Data Deficient. Store fish are commercially bred, so buying one doesn’t pressure wild populations.
The number that matters: a ceiling, not a target
The sources don’t agree on how cold white clouds like it, but they do agree on how warm. Seriously Fish gives 14–22°C (57–72°F). FishBase gives 18–22°C, and separately notes the species can survive water as cold as 5°C. That’s a survival record, not a goal. Both stop at about 22°C (72°F).
Seriously Fish adds that keeping them warmer permanently is “likely” to shorten their lives. That’s an informed caution, not a measured lifespan figure. A thermometer tells you whether your room suits them. Check it on the warmest afternoon, not just the coldest night.
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What keeps him well
- Keep him out of the tropical community tank. He’s peaceful enough, but a tropical heater keeps him above his range around the clock.
- Not with goldfish, either. White clouds are often sold as goldfish companions, and Seriously Fish says plainly that they don’t make good ones. (Our goldfish tank-size myth post covers what goldfish need instead.)
- A real group. FishBase says groups of 5 or more, and Seriously Fish says 10 or more. Bigger schools mean calmer fish and brighter males.
- Room to swim. Seriously Fish’s minimum footprint is 60 × 30 cm (24 × 12 in), about 14 US gallons. Dense plants and a dark substrate both help.
- Choose stock carefully. Seriously Fish warns that inbreeding in farm stock has left many fish weak or deformed. Pick active, full-bodied fish, and if one looks sick after you bring it home, call an aquatic vet.
Keeping a heated tank too? Run our heater check before the cold nights.
The takeaway: the white cloud is a hardy, cheerful fish that doesn’t need a heater. Give him cool water, a proper school, and no goldfish for company.
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