Top 10 Coldwater Fish That Don't Require a Heater

This article lists the top 10 coldwater fish that can be kept successfully without a heater in a home aquarium. These fish can survive in water as chilly as 65 degrees Fahrenheit, making them great for ponds in the great outdoors. We'll take a closer look at what makes these fish so special, how to best care for them, and why you should add them to your aquarium. What are we waiting for?

1. Sunset Variatus

The Sunset Variatus is one of the author's favourite species of coldwater fish. The brilliant colours and resilience of this live-carrier fish have made it a popular pet. The lowest temperature at which it can survive is 65 degrees Fahrenheit, and it can grow to a length of 2-3 inches. This fish will flourish in an aquarium with a pH of at least 7, some live plants, and peaceful tank mates.

2. Galaxy Rasbora, or Celestial Pearl Danio

Celestial Pearl DanioThe Galaxy Rasbora, or Celestial Pearl Danio, is a nano fish that can survive in temperatures as low as ten degrees Fahrenheit. It's peaceful nature makes it a good fit for tiny aquariums with peaceful fish like platies. They do well in moderately hard water between the pH levels of 6.8 and 7. These solitary fish thrive in groups of six or more and favour little meals.

3. Rainbow Shiner

The Rainbow Shiner is a kind of native fish to the United States; it matures to a magnificent purple and pink coloration. It grows to a length of 3.3–3.5 inches and thrives in waters with lower temperatures. Surprisingly, they don't bother the guppies or the endlers, and vice versa. However, you may have trouble tracking them down.

4. Hillstream Loach

Hillstream LoachThe Hillstream Loach is a great fish for unheated aquariums since it eats algae. Their appearance is reminiscent of extraterrestrial stingrays, and they feed on flat algae and diatoms while clinging to the sides of the aquarium. They can be kept in groups of one or more and thrive in an environment with a pH between 6.7 and 7.8. It's suggested that the tank be at least 20 gallons in size.

5. Endlers Livebearer

The Endlers Livebearer is a robust little fish that does fine at room temperature, making it our number five pick. They're able to reproduce quickly and available in a wide range of colours. They do well in water with a pH of 6.8.6, and their minimum tank size is only 5 gallons. Adding in a variety of additional species and a planted aquarium will make for a lively and interesting environment.

6. Clown Killifish

Clown Killifish, number six on our list, are an interesting addition to any coldwater aquarium because they live in the aquarium's uppermost layers. They can survive for more than a year in a pH range of 6.5-7.8. They are peaceful and compatible with other community fish despite their intimidating moniker. They have a tendency to jump out of the tank, thus a lid is necessary.

7. Cherry Shrimp

Cherry ShrimpCherry Shrimp are not only beautiful but also great cleansers for your aquarium. They can survive in frigid climates and quickly proliferate. You can get them from a lot of different stores and bars around town. They're tolerant of other fish, especially hillstream loaches, but need a steady supply of calcium in the water.

8. Dojo lach, or weather lach

Dojo lach, or weather lach, is a rare species of bottom-dwelling fish that can reach a maximum length of 10 inches. They can dig tunnels in the gravel and have a lively disposition. They do well with other medium-sized fish like barbs and require a pH of 6-8. However, they could consume prawns or other small fish, so exercise caution.

9. Rosy Barb

The Rosy Barb is a fast, versatile fish that can survive in cooler waters. Many species exist, and they are compatible with other fish of a similar size range. They are cheap and widely available, and they like a pH of 6.6 to 8.6.

10. White Cloud Mountain Minnow

White Cloud Mountain MinnowThe White Cloud is a tough and adaptable fish that thrives in a wide range of water conditions. They are a long-time favourite of aquarists since they may be used in aquariums of any size. The "poor-man's neon tetra" is a common nickname for these fish because of their understated elegance.


Aquarists who want to set up an outdoor pond or an aquarium that doesn't need to be heated have a lot of alternatives among the top 10 coldwater fish. These fish come in a wide range of colours, sizes, and behaviours, from bright live-bearers to unusual bottom-dwellers. You can make a beautiful and successful coldwater aquarium if you know how to take care of the fish and other tank inhabitants properly.

Here is a table of aquarium fish and other species with columns for their common names, scientific name, suitability for community aquariums, optimum temperature, optimum pH, and any other useful data:

Common Name Scientific Name Suitability for Community Aquariums Optimum Temperature Optimum pH Other Useful Data
Cory Catfish Corydoras spp. Excellent 72-78°F 6.0-7.5 Peaceful bottom-dwellers
Neon Tetra Paracheirodon innesi Excellent 70-81°F 6.0-7.5 Peaceful schooling fish
Guppy Poecilia reticulata Excellent 72-82°F 7.0-8.5 Easy to breed
Zebra Danio Danio rerio Excellent 64-75°F 6.5-7.5 Active schooling fish
Swordtail Xiphophorus hellerii Excellent 72-82°F 7.0-8.5 Easy to breed
Cherry Barb Puntius titteya Excellent 72-78°F 6.0-7.0 Peaceful schooling fish
Harlequin Rasbora Trigonostigma heteromorpha Excellent 72-77°F 6.0-7.0 Peaceful schooling fish
Platy Xiphophorus maculatus Excellent 72-82°F 7.0-8.5 Easy to breed
Bristlenose Pleco Ancistrus spp. Good 72-82°F 6.5-7.5 Peaceful bottom-dweller
Kuhli Loach Pangio kuhlii Good 75-86°F 6.0-7.0 Peaceful bottom-dweller
Otocinclus Catfish Otocinclus spp. Good 72-78°F 6.5-7.5 Peaceful algae-eater
Celestial Pearl Danio Danio margaritatus Good 72-78°F 6.0-7.0 Peaceful schooling fish
Endler's Livebearer Poecilia wingei Good 72-82°F 7.0-8.5 Easy to breed
Rosy Barb Puntius conchonius Good 72-78°F 6.0-7.0 Peaceful schooling fish
Dwarf Gourami Trichogaster lalius Good 72-82°F 6.0-7.5 Peaceful mid-level swimmer
Pearl Gourami Trichogaster leeri Good 72-82°F 6.0-7.5 Peaceful mid-level swimmer
Black Skirt Tetra Gymnocorymbus ternetzi Good 72-78°F 6.0-7.5 Peaceful schooling fish
Cardinal Tetra Paracheirodon axelrodi Good 72-82°F 5.0-7.0 Peaceful schooling fish
German Blue Ram Mikrogeophagus ramirezi Good 78-85°F 6.0-7.0 Peaceful mid-level swimmer
Cherry Shrimp Neocaridina davidi Good 68-78°F 6.5-8.0 Peaceful algae-eater
Mystery Snail Pomacea bridgesii Good 68-82°F 7.0-8.0 Peaceful algae-eater
Apple Snail Pomacea canaliculata Good 68-82°F 7.0-8.0 Peaceful algae-eater
African Dwarf Frog Hymenochirus spp. Good 72-82°F 6.5-7.5 Peaceful bottom-dweller


Does a heater really help cold-water fish?

As their name suggests, coldwater fish are able to survive in cooler waters than their tropical counterparts. It is important to learn the precise temperature needs of the fish you intend to keep, as some coldwater fish species can do well without a heater. A heater may still be useful for some cold-water fish that require a constant temperature. What kinds of fish can live in cold waters? There are many fish species that can tolerate and even flourish in cold water. White Cloud Mountain Minnows, Celestial Pearl Danios, Hillstream Loaches, Goldfish, and Cherry Shrimp are just a few examples of well-liked fish species. These fish are hardy and have adapted to colder temperatures.

Which fish can live without a heater or filter?

While filters and heaters are generally recommended for aquariums, there are a few fish species that can do just fine without them. White Cloud Mountain Minnows and Hillstream Loaches are two examples of hardy coldwater fish that may thrive without heaters in their aquariums. However, keep in mind that even under these scenarios, a healthy and balanced aquarium ecosystem still need regular water changes and careful maintenance.

Can cold-water fish adapt to warmer temperatures?

Fish that thrive in colder temperatures may not fare as well in warmer waters. Stress or death can result from exposure to extreme heat, either temporarily or permanently. To keep your cold-water fish healthy, you must create a habitat that meets their special temperature requirements.

Do novices fare well when they begin with cold-water fish keeping?

Beginners may find excellent success with an aquarium by starting with cold-water fish. Fish native to colder waters are typically more robust and can survive with less care than their tropical counterparts. However, it is still vital to learn about and meet the requirements of the fish you intend to keep, create an appropriate environment for them, and keep the water quality high by consistent monitoring and upkeep.