Best Coldwater & Unheated-Tank Fish

Species that thrive in cool or room-temperature water, without a heater.

By The Aquarium DB Team • 29 species
Cherry Shrimp Cherry Shrimp Gold Ring Danio Gold Ring Danio Ghost Shrimp Ghost Shrimp Golden Dwarf Barb Golden Dwarf Barb Amano Shrimp Amano Shrimp Japanese Trapdoor Snail Japanese Trapdoor Snail Zebra Danio Zebra Danio Bloodfin Tetra Bloodfin Tetra Desert Goby Desert Goby Buenos Aires Tetra Buenos Aires Tetra Peppered Corydoras Peppered Corydoras Roundtail Paradise Fish Roundtail Paradise Fish Gold Barb Gold Barb Mexican Tetra Mexican Tetra Rosy Barb Rosy Barb Murray River Rainbowfish Murray River Rainbowfish Weather Loach Weather Loach Spotted Pleco Spotted Pleco Northern Glowlight Danio Bearded Corydoras Bearded Corydoras Butterfly Hillstream Loach Butterfly Hillstream Loach Paradise Fish Paradise Fish Denison Barb Denison Barb Goldfish Goldfish Panda Loach Imperial Flower Loach Imperial Flower Loach Koi Koi Spotted Gar Spotted Gar Wels Catfish Wels Catfish
Buyer's guide

How to choose a coldwater fish

Coldwater fish do best below the tropical range, which makes them ideal for unheated tanks in a heated home — or, for the bigger species, for ponds. Note that "no heater" does not mean "no filter": coldwater favourites like goldfish and koi are large, messy fish that need serious filtration and space.

Do not mix true coldwater fish with tropical species — their temperature needs simply do not overlap. Several tolerant tropicals (like zebra danios) appear here because they cope with cooler rooms, but they are happiest with fish that share their range.

FAQ

Frequently asked questions

Do goldfish really need a big tank?

Yes. Common goldfish reach 30 cm and live well over a decade, producing a lot of waste. They need a large, heavily filtered tank or a pond — never a bowl.

Can coldwater and tropical fish live together?

Generally no. Coldwater species want roughly 15–22 °C while tropical fish want 24–28 °C, and the ranges do not overlap. Pick one temperature world and stock to it.