The white cloud mountain minnow is a small, hardy fish from cool mountain streams near Guangzhou in southern China, marked with a red-and-iridescent stripe.
It is now rare in its native range but breeds readily and thrives in aquariums.
It is one of the few common community fish that needs no heater, tolerating cool room temperatures with ease.
Forgiving and beginner-friendly, it is a good first shoaling fish, though it dislikes prolonged tropical warmth.
Housing
A shoal of six or more does well in 40 litres (10 gallons) or more, filtered, with no heater required.
They thrive at 16-22C and suffer at sustained tropical temperatures, making them well suited to unheated rooms and some outdoor ponds in mild climates.
They are active swimmers that appreciate length, gentle current and planted edges.
Tolerant of a wide range of water chemistry, they need only a stable, well-cycled tank and a secure lid, as they can jump.
Diet
White clouds are easy-going omnivores that feed at the surface and in midwater.
A quality flake or micro-pellet serves as a reliable staple, rotated with frozen or live daphnia, brine shrimp and bloodworm to support their colours.
Feed small amounts once or twice daily, only what is eaten quickly.
They forage actively and rarely refuse food, so measured portions and the occasional fasting day keep the water clean and the fish in good condition.
Health
Among the hardiest aquarium fish, white clouds suffer few ailments when kept cool and clean.
Most problems, such as ich or fin rot, follow overheating, poor water quality or stress rather than inherent fragility.
Keeping them at tropical temperatures long term shortens their lives and dulls their colour, so avoid heating the tank.
Quarantine new stock, maintain weekly partial water changes, and fit a lid to prevent jumps.
Temperament
Peaceful, active and confident, white clouds shoal loosely and look best in good numbers, where males flare their fins at one another harmlessly.
They are too gentle to bother any reasonable tankmate.
They suit calm, cool-water communities and pair well with other temperate species.
Avoid housing them with warmth-loving tropicals whose needs conflict, or with large fish that may eat them.
A good fit for
Beginners and first aquariums
Unheated, cool-room or temperate setups
Outdoor ponds in mild climates
Peaceful cool-water community tanks
Common mistakes to avoid
Keeping them in warm tropical tanks long term
Keeping too few, dulling colour and behaviour
Open tanks they can jump from
Pairing with warmth-loving or large fish
Is your enclosure big enough?
Minimum volume40 litres (11 US gallons)
CompanyCannot be kept alone. The minimum is 6, and the space above is for that group.
In a fish tank the patient is usually the water. Test before you treat — dosing a healthy tank for a disease it does not have makes things worse.
Go now
Any detectable ammonia or nitrite in a stocked tankLarge water change now with dechlorinated, temperature-matched water. Stop feeding. Test again in 12 hours. Both are directly toxic. How toxic the ammonia reading is depends on pH and temperature, so the same number can be harmless or lethal.
Now
Fish gasping at the surface, or crowding the filter outflowIncrease surface agitation immediately, then test the water. Either the oxygen has crashed or the gills are being chemically burned. Both are hours-scale problems.
Now
Sudden deaths, more than one fish in a dayTest ammonia, nitrite, nitrate and temperature before doing anything else. Do not add medication yet. Multiple simultaneous deaths point at the water or the equipment, not at a pathogen.
Now
Today
Flashing — repeatedly scraping against decor or substrateTest the water, then look closely for parasites. Irritation is either chemical or parasitic; the test tells you which before you medicate.
Today
White salt-grain spots over the body and finsBegin the appropriate treatment today and check the temperature. The parasite's life cycle is temperature-driven, and it multiplies with every cycle you wait.
Today
Soon
Clamped fins, hiding, or refusing food for more than two daysTest the water and review recent changes. Usually the earliest visible sign of a parameter drifting.
A few days
Never add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
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