10 Coldwater Fish That Don’t Require Heaters

Written By

Mathew Abraham

Updated on

Mathew Abraham

Meet Mathew, Cat Dad and Animal Advocate! Mathew is the editor at PawDown, overseeing content strategy and quality. He's in charge of carefully curating the best pet stories, tips, and advice for you.

small fish
geraldrose/Pixabay

Maintaining a cold-water aquarium is an excellent choice for aquarists who prefer a simpler setup without the need for heaters. Coldwater fish are hardy, beautiful, and can adapt to a wide range of conditions, making them ideal for both beginners and experienced hobbyists. From small, colorful species to more unique and interesting choices, these fish bring life and vibrancy to any tank. Let’s see ten amazing coldwater fish species that thrive without heaters, each offering their unique characteristics and charm.

1. Endler’s Livebearer

Endler’s Livebearer fish
Cinder1977/Reddit

The Endler’s Livebearer is a bright and lively fish, perfect for aquarists seeking a colorful and low-maintenance addition to their tanks. Known scientifically as Poecilia wingei, this species is part of the guppy family and thrives in water temperatures between 64°F and 82°F, making it ideal for unheated tanks. Their small size, averaging 2 inches, allows them to fit comfortably in tanks as small as 20 gallons. Peaceful and active, they coexist well with other non-aggressive fish. Their vibrant colors and adaptability make them a favorite for both beginners and seasoned aquarists.

2. Bloodfin Tetra

Bloodfin_Glass_Tetra-2
Chronotopian/WikimediaCommons

Bloodfin Tetras are a delightful choice for any cold-water aquarium. These small, shimmering fish, recognizable by their silver bodies and bright red fins, thrive in temperatures ranging from 64°F to 82°F. Low-maintenance and hardy, they adapt well to various pH levels and tank setups. Typically kept in schools, their social nature adds dynamic movement to tanks of at least 20 gallons. Bloodfin Tetras are peaceful, making them excellent companions for other calm species. Their striking appearance and easy care make them a top pick for aquarists at all experience levels.

3. Odessa Barb

Odessa_barb_male
AnandaRajkumar/WikimediaCommons

The Odessa Barb is an underrated gem in the aquarium world, known for its striking, red-tinted body and energetic personality. This hardy species thrives in water temperatures between 70°F and 79°F and requires a tank of at least 30 gallons to accommodate their active swimming. They’re peaceful when kept in schools and compatible with a variety of tank mates. Their diet is flexible, ranging from flakes to live foods, making them easy to care for. The Odessa Barb’s vibrant appearance and adaptable nature make them a captivating addition to any cold-water setup.

4. White Cloud Mountain Minnow

White cloud
Corydoras-adolfoi/WikimediaCommons

The White Cloud Mountain Minnow is a small, graceful fish that thrives in cooler temperatures, ranging from 64°F to 72°F. Often compared to Neon Tetras for their appearance, they’re low-maintenance and ideal for beginners. With an average size of 2 inches, they can comfortably inhabit tanks as small as 10–15 gallons. These fish are social and do best in groups, adding constant activity to your aquarium. They adapt well to various tank setups and are compatible with peaceful tank mates, making them a reliable and charming choice for cold-water environments.

5. Sunset Variatus Platy

Sunset Variatus Platy
Ok_Recognition6366/Reddit

The Sunset Variatus Platy is a colorful and versatile fish, perfect for aquarists seeking a vibrant species for their tanks. With shades of yellow, orange, and red, this platy is visually stunning. They thrive in water temperatures from 72°F to 82°F and can adapt to slightly cooler tanks as well. Reaching about 2.5 inches in length, they are peaceful and easy to care for, ideal for community tanks of at least 15 gallons. Their bold colors and active behavior make them a favorite for hobbyists looking to add a splash of brightness to their aquariums.

6. Panda Corydoras

Panda Corydoras
By Chronotopian – Own work, CC BY-SA 3.0_ Wikimedia Commons

Panda Corydoras are charming and peaceful bottom-dwellers, easily recognized by their black and white “panda-like” markings. Thriving in water temperatures of 68°F to 77°F, they are ideal for cold-water aquariums. These fish grow to about 2 inches and require a tank of at least 10 gallons. Panda Corydoras are social and should be kept in groups of three or more, adding lively activity to the tank’s lower levels. They’re relatively easy to care for, making them a popular choice for community aquariums with peaceful tank mates.

7. Fancy Goldfish

fancy Goldfish
Hans/Pixabay

Fancy Goldfish are an elegant and iconic choice for cold-water aquariums, known for their unique body shapes, flowing fins, and vivid colors. Unlike standard goldfish, Fancy Goldfish thrive in water temperatures as low as 50°F, eliminating the need for a heater. They grow larger than many other species, so tank size varies by type, but a spacious setup is essential. Peaceful and hardy, they coexist well with similarly tempered species. Their beauty and adaptability make them a classic choice for aquarists of all experience levels.

8. Mosquito Fish

Mosquito Fish
Nozo/WikimediaCommons

Mosquito Fish are hardy and practical additions to cold-water tanks, thriving in temperatures between 65°F and 75°F. Often used in ponds for their ability to control insect larvae, they are equally suited for aquariums of at least 20 gallons. These small, energetic fish grow up to 3 inches and are low-maintenance, requiring minimal effort to keep healthy. Though generally peaceful, occasional aggression can occur, so careful selection of tank mates is recommended. Their resilience and utility make them a fascinating and functional choice for cold-water setups.

9. Bristlenose Pleco

Bristlenose Pleco
fish_are_frnds/Reddit

The Bristlenose Pleco is a unique and hardy addition to cold-water aquariums. Known for the bristle-like appendages on their noses, these fish thrive in water temperatures from 60°F to 80°F. Growing up to 5 inches, they require a tank of at least 25 gallons. As algae eaters, they contribute to tank cleanliness while being peaceful and compatible with most species. Their unusual appearance and practicality make them a favorite among aquarists seeking a low-maintenance, functional fish for their tank.

10. Rosy Red Minnow

Rosy_Red_Minnows_fullsize
Enziaro/WikimediaCommons

Rosy Red Minnows are small, hardy fish that thrive in water temperatures as low as 50°F, making them ideal for unheated tanks. Growing up to 3 inches, they adapt well to tanks as small as 10 gallons, although larger setups are preferred for groups. Their peaceful temperament allows them to coexist with a variety of species. These minnows are low-maintenance and versatile, requiring no specific habitat features. With their soft pink hue and active nature, they are both visually appealing and easy to care for in cold-water environments.

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