20 Best Cold Water Fish That Don't Require A Heater

1. Goldfish

• Lifespan: over 10 years
• Size: up to 12 inches
• Tank Requirements: pH of 7.0 to 8.4
• Water Hardness: 5-19dGH
• Temperature: (65-75)°F

They can grow up to 12 inches of life over 10 years, thrive in spacious tanks and are famous for their bright orange colors with variations in red, white, and black.

Their temperament is peaceful but they can be territorial if the tank is overcrowded. They are omnivorous, feeding on flakes and pellets, and they can feed veggies occasionally.

They are easy to moderate to care for and require regular water changes as they produce a lot of waste and need care. They are best with other goldfish or similar cold-water species.

2. White Cloud Mountain Minnow

• Lifespan: 5-7 Years
• Size: up to 1.5 Inches
• Water Requirements: (6.0-8.0)pH 
• Water hardness: 5-19 dGH
• Temperature: 60-72 F

Founded by the people of the White Cloud Mountain region of China, they are small fish growing up to 1.5 inches. They have silvery bodies with red fins and striking blue stripes and are known as the "neon of the poor man".

They have a peaceful and sociable temperament, perfect for common tanks and ideal for beginners, and they are hardy and adaptive. As omnivorous as they are, they like small flakes, brine shrimp, and daphnia and are easy to breed by lying egg on plants.

3. Bristlenose Pleco

• Lifespan: up to 12 years
• Size: up to 5 inches
• Tank Requirements: pH of 6.5-7.5
• Water hardness: 6-10dGH
• Temperature: 60-77 F

Being native to the rivers of South America, it is a peace-loving fish and great for community tanks. They are brown or black with white spots and distinctive bristles on their noses.

They feed on algae, zucchini, and sinking pellets as they are herbivorous and they are best for beginners as they need low maintenance and are known for their excellent algae eaters and helping to keep the tank clean.

4. Zebra Danio

• Lifespan: 3 to 5 years
• Size: Up to 2 inches 
• Tank Requirements: pH (6.5-7.2) 
• Water hardness: (5-12)dGH
• Temperature: (64-75) F

Emerging from the streams of India and Bangladesh, they are active fish growing up to 2 inches with a lifespan of 3 to 5 years. They have blue and silver stripes with slender bodies of peace and social temperament and like to stay in the group.

They are peaceful and socially loved to be in groups and are omnivorous and enjoy flakes, frozen food, and live foods. They are egg-laying fish and are known for scientific research due to their genetic similarity to humans.

They are best kept with the most non-aggressive species and are the most popular fish for the aquarium hobby as they are very playful and adaptable making them great choices for both novice and experienced fish keepers.

5. Rosy Barb

• Lifespan: 5 years
• Size: up to 6 inches
• Tank Requirements: pH of 6.0-8.0
• Water hardness: 5-19 dGH
• Temperature: 64-72°F

Rosy Barb is a very attractive, hardy fish that is pink to red in color and glitters in the light to give a great deal of imaginative display under aquarium lights Their semi-aggressive nature is best managed by keeping them in schools, which allows them to display their natural, synchronized swimming behavior.

Rosy Barbs are omnivores and enjoy a varied diet, which includes flakes, vegetables, and live foods. They are relatively easy to care for but still require a moderate level of attention because of their active nature.

6. Rainbow Darter

• Lifespan: 2-4 years
• Size: 3 inches
• Tank Requirements: pH of 6.5-8.0 
• Water hardness: 5-15 dGH
• Temperature: 50-70°F  

Small, native to North America, with a lifespan of 2-4 years with bright blue or orange stripes, especially vivid in males, are peaceful freshwater fish suitable for the in-house aquarium setup.

They are carnivorous and feed on small invertebrates and live and frozen foods requiring clean, well-oxygenated water and a strong current. They are well known for darting behavior which means quickly moving from one spot to another in search of foods and they are best suited with the other darter fish groups.

7. Paradise Fish

• Lifespan: up to 8 years
• Size: up to 3inches
• Tank Requirements: pH of 6.0-8.0
• Water hardness: 5-30 dGH
• Temperature: 61-79°F  

Paradise fish are one of the most beautiful and hardy species in most aquariums with bright blue and red long, flowing fins. Since they are known to be semi-aggressive, especially males, paradise fish should either be kept in fast-moving fish tanks or as lone occupants. These are omnivorous fish that eat flakes, live foods, and frozen foods.

They are moderately easy to care for but can be quite aggressive toward their tankmates, so care should be taken in selecting companions. Paradise Fish raise bubble nests, and the males take on the protective role of guarding the nest. They have a labyrinth organ, which makes them capable of direct air-breathing and adaptable to a great variety of aquatic conditions.

8. Hillstream Loach

• Lifespan: 8 to 10 years
• Size: up to 3 inches
• Tank Requirements: pH of 6.5-7.5
• Water hardness: 10-15 dGH
• Temperature: 68-75°F  

Hillstream loaches are the most fascinating creatures, with flattened body shapes and intricate, patterned appearance. Their docile disposition, combined with the necessity for strong currents, makes them an attractive addition to the most well-oxygenated tanks.

Being mostly herbivorous, the Hillstream Loaches do very well on a diet of biofilm, algae, and sinking wafers, hence constantly making them an excellent choice for algal control in aquariums. They can be kept with other peaceful species in a well-structured aquarium with ample surface area for them to latch onto, assisted by their unique sucker mouths.

Breeding in captivity is not simple because there are specific requirements. However, the sight of them in a fish tank sliding against the glass and rocks is just heavenly as they can only bring to one's imagination small stingrays.

9. Rainbow Shiner

• Lifespan: 3-4 years
• Size: up to 3 inches
• Tank Requirements: pH of 6.5-8.0   
• Water hardness:  10-20 dGH
• Temperature: 50-75 °F  

Rainbow Shiners belong to small, strikingly attired fish that make any fish tank look amazing and are very active and peaceful fish that should be in schools to appreciate their animated behavior fully and do well with clean and oxygen-rich water. Their compatibility with other peaceful fish is quite good; they can thrive in a community tank setting.

Being omnivorous, Rainbow Shiners enjoy small live foods and quality flakes. They are not too demanding and require an aquarist with little experience to tend them. 

Their breeding ground is of cooler waters with rocky bottoms where their colors tend to become even brighter. This is an excellent species to give a beautiful display in an aquarist tank in terms of colorful looks and active behaviors.

10. Peppered Corydoras

• Lifespan: 5 to 10 years
• Size: up to 3 inches
• Tank Requirements: pH of 6.0-7.0
• Water hardness:  2-12 dGH
• Temperature: 64-72 °F  

Gray-black has barbels on the snout, which are used while digging for food in the substrate. Peaceful and social, they do well in groups, hence fitting perfectly in community tanks.

These omnivores will chew up sinking pellets, algae wafers, and even live foods like bloodworms. They're so easy to care for that beginners can keep them, although they will all readily adapt to most conditions with a pH of 6.0 to 7.0 and temperatures within the range of 64-72°F.

Beyond the cleaning role attributed to them as a result of their scavenging behavior, they are known to "wiggle" in an excited manner, especially at feeding times. Breeding is not that difficult since they are egg layers; females will typically lay their eggs on surfaces within the tank, mostly on the glass.

11. Buenos Aires Tetra

• Lifespan: 5-6 years
• Size: up to 2.75 inches
• Tank Requirements: pH of 6.0-8.0
• Water Hardness: 6-20 dGH
• Temperature: 64-82°F  

The Buenos Aires Tetras are full of life, and hardy, therefore add much energy to any aquarium. They are silver-colored bodies with rather bright, distinctive red tails and fins, making them stand out in a community tank in large numbers.

These tetras are omnivores and prefer flake, live, and frozen foods in their diet. It's easy to maintain but expect to make lots of water changes to keep them in the best health and fitness. They are semi-aggressive by nature, thus needing a great deal of attention when selecting tankmates

12. Emerald Dwarf Rasbora

• Lifespan: 3 to 5 years
• Size: up to 1 inch
• Tank Requirements: pH of 6.5-7.5
• Water hardness: 5-12 dGH
• Temperature: 68-75°F  

They are tiny fish with an iridescent green body with vertical blue stripes and red fins, growing up to 1 inch, with a lifespan of 3-5 years. They are peaceful and shy in temperament and are best kept in groups.

They are omnivorous and enjoy small flakes, micro-pellets, and live foods, and need a moderate level of care with a well-planted tank with sufficient hiding spots. They are compatible with other small and peaceful fish..

These are egg scatterers and breeding requires cooler water dense vegetation and 
their small size and vivid colors make them popular in aquascaped tanks.

13. Mosquitofish

• Lifespan: Up to 2-3 years
• Size: Up to 2.8 inches (females) / 1.6 inches (males)
• Tank Requirements: pH of 6.5-8.0 
• Water Hardness: 10-20 dGH
• Temperature: 50-86°F  

They are small, hardy fish known for their ability to control the population of mosquitoes by feeding on larvae. In mosquitofish, females are larger than males, and have the appearance of grayish or olive coloration.

They are omnivorous and feed on algae, insects, commercial fish flakes, and mosquito larvae. As they thrive in various water conditions, they are easy to care for and can be great choices for outdoor ponds or unheated aquariums.

14. Bloodfin tetra

• Lifespan: 5-8 years
• Size: Up to 2 inches
• Tank Requirements: pH of 6.0-8.0
• Water Hardness: 2-15 dGH
• Temperature: 64-82°F

They are famous for their striking appearance with a silver body with bright red fins that add vibrant effects of color to any aquarium. These peaceful, schooling fish thrive in groups where they can show their natural, coordinated swimming behaviors.

While omnivorous, they thrive on various types of diets including flakes, small insects, and plant matter. They are hardy and adaptable, which makes them everyone's choice for beginners.

15. Dojo Loach

• Lifespan: 7-10 Years
• Size: up to 10 Inches
• Water Requirements: (6.0-8.0)pH 
• Water hardness: 5-12 dGH
• Temperature: 50-77°F

The Dojo Loach, also called the Weather Loach, is an interactive fish that is known for its playful and burrowing nature. They are from East Asia, reaching 10 inches in length with a 7-10 year life expectancy.

They have an elongated, eel-like body with light brown to yellow coloration that allows them to blend into their environment. They are non-aggressive fish that do well with a pH of 6.5-8.0, water hardness of 5-12 dGH, and temperature from 50-77°F.

The Dojo loaches are omnivorous and eat sinking pellets, frozen foods, and small crustaceans. They are of medium-easy care; quite adaptable to various conditions, they are suitable for beginning and experienced aquarists alike.

16. Gold Barb

• Lifespan: 5-7 years
• Size: up to 3 inches
• Tank Requirements: pH of 6.0-8.0
• Water hardness: 5-19 dGH
• Temperature: 64-75°

They have the appearance of a golden-yellow body with black markings along the sides and are of semi-aggressive temperament, so it's best to keep them in schools to minimize aggression.

They are omnivorous and thrive on a diet of flakes, vegetables, and live foods and they are best suited for those who are beginners or intermediate hobbyists as they require moderate care 

Gold Barbs are not only visually appealing but also easy to care for, making them a great choice for community tanks. Their vibrant color and active nature can brighten up any aquarium.

17. Northern Redbelly Dace

• Lifespan: Up to 3-5 years
• Size: Up to 3 inches
• Tank Requirements: pH of 6.5 to 8.0
• Water Hardness: 5-19 dGH
• Temperature: 50-70°F

Small fish, found in cool, clear, streams and ponds with silver bodies with distinctive red bellies and black stripes during breeding seasons. They show peaceful temperament and they are best kept in groups.

They enjoy omnivorous flakes, small insects, and algae, and are compatible with other peaceful, cool water species. They breed in spring seasons and require cooler water and specific substrates.

18. Medaka

• Lifespan: up to 3-5  years
• Size: up to 1.5  inches
• Tank Requirements: pH of 7.0-8.0 
• Water hardness: 9-19  dGH
• Temperature: 64-75°F  

The Medaka, or Japanese rice fish, are small, hardy fish that seem to carve a space for themselves in aquascaping. The body of the medaka is slender and transparent, and its color ranges from gold to pale orange. They are ideal to cohabit in small community tanks as they are peaceful and resilient and will coexist with other non-aggressive small fish.

These omnivores will do well with a diet based on small flakes, micro-pellets, and some live foods like brine shrimp. They are easy to breed since the female releases her eggs by expelling them onto plants. 

19. Banded Killifish

• Lifespan: 3-5 years
• Size: 4 inches
• Tank Requirements: pH of 6.5-8.0
• Water hardness: 5-19 dGH
• Temperature: 60-75°F

They have olive-green bodies with horizontal black stripes and a slight iridescent sheen and are peaceful, but they can be territorial in smaller tanks.

While omnivorous, they feed on flakes, live, and frozen foods and are good with peaceful fish but may chase smaller species. They are hardy and capable of adopting a range of conditions.

For breeding, they spawn in shallow water with dense vegetation and they are suitable to keep outdoor ponds in cooler climates.

20. Red Shiner

• Lifespan: 3-4 years
• Size: 3 inches
• Tank Requirements: pH of 6.5-8.0
• Water hardness: 5-15 dGH
• Temperature: 60-75°F

They are small fish and peace-loving fish growing up, and are native to North America, particularly the Mississippi River basin. They have a silver body with a brilliant red head and fins, especially during breeding season.

They are omnivorous; they feed on flakes, live, and frozen foods. They are hardy and tolerant of a range of conditions suitable for community tanks with other peaceful species. They are often used as baitfish, but their vibrant colors make them a beautiful addition to home aquariums.