27 Best Cold Water Fish For Your Aquarium (No Heater)

If you’re thinking about getting some cold water fish for your tank, you will have a lot of options. In fact, there is an abundance of different types to choose from that some aquarists have hard time picking!

This guide will help you in this regard.

In it, you’ll learn more about all the best fish for cold water tanks. Many don’t even need heaters!

By the time you finish reading it, you’ll know which species interest you the most.

1. Endler’s Livebearer

The Endler’s Livebearer is an excellent addition to your cold water aquarium. They do not only possess stunning colors, but caring for them is easy as well.

This fish is occasionally referred to as Poecilia wingei since it’s technically part of the common guppy family. These fish are quite hardy and can tolerate various water conditions and habitats.

When it comes to water temperature, they can tolerate a wide range of temperatures from 64°F to 82°F. This is not only very generous, but rather chilly as well.

We highly recommend these fish to pretty much any aquarist. Not just those looking for cold water fish, as they are a strong choice in general.

• Size: 2 inches
• Difficulty: Beginner
• Minimum Tank Size: 20 gallons
• Water Temperature:

2. Bloodfin Tetra

Bloodfin Tetras are a species we admire due to their low-maintenance nature, beautiful appearance, and their ability to get along with a large number of other fish.

Their simply color combination makes observing then them in a group a delightful experience , these fish are relatively small , and can be kept in a pretty small tank.

When it comes to setting up their habitat there’s not much to be concerned about as well. They can thrive in cold water, tolerate a range of pH levels, and adapt to various decorations and layouts. Simply drop in some plants and you’ll be just fine!

• Size: 2 inches
• Difficulty: Beginner
• Minimum Tank Size: 20 gallons
• Water Temperature: 64°F to 82°F

3. Odessa Barb

Freshwater aquarists tend to overlook Odessa barbs, and for some reason, these fish don’t receive the attention they deserve. We’ve been admiring them for years and love the adaptability that their hardy nature provides. They thrive in cooler waters and will peacefully coexist with a variety of different tank mates.

Provided that their diet is diverse and their habitat is stable, Odessa Barbs will lead contented lives. Additionally, if you are interested in breeding, they can reproduce successfully in captivity.

• Size: 3 inches
• Difficulty: Beginner
• Minimum Tank Size: 30 gallons
• Water Temperature: 70°F to 79°F

4. White Cloud Mountain Minnow

The White Cloud Mountain Minnow is a great freshwater fish that do best in colder temperatures. They’re a species that doesn’t get much recognition, but that’s something we’ve never understood.

People often compare this fish to Neon Tetras due to their similar appearance. They’re easy to care for, quite affordable, and are compatible with many different kinds of fish.

We often recommend this species to aquarists, as they make for a delightful addition to any tank .They can adapt to various types of habitats without encountering significant difficulties.

• Size: 2 inches

• Difficulty: Beginner
• Minimum Tank Size: 10-15 gallons
• Water Temperature: 64°F to 72°F

5. Sunset Variatus Platy

This is a type of platy is not commonly discussed. But if we had to make a decision, this would probably be our favorite!

The Sunset Platy is a versatile fish that can do well in a number of different conditions. They’re relatively low-maintenance and can thrive in slightly cooler water.

Their beauty is simply breathtaking! it is one of the most colorful freshwater species you will come across. Watching them swim around in the tank is addicting. There are only a handful of fish with a bright yellow that can compete with the Sunset Variatus Platy.

For those seeking colorful cold water fish, we recommend giving these creatures a shot.

• Size: 2.5 inches
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: 15 gallons
• Water Temperature: 72°F to 82°F

6. Panda Corydoras

This is one of the most popular fish among aquarists. The Panta Cory is a species that can be found all over the world, and for good a good reason.

They have beautiful appearance and a neat color pattern. This makes them a great fish to watch.

Their care is quite straightforward as well. As long as you understand their fundamental maintaining this fish should pose no difficulty.

Their peaceful temperament gives you a lot of options when it comes to tank mates as well. This is why Panda Corydoras are often chosen for community tanks.

• Size: 2 inches
• Difficulty: Intermediate
• Minimum Tank Size: 10 gallons
• Water Temperature: 68°F to 77°F

7. Fancy Goldfish

Fancy goldfish are a popular type of goldfish known for their intricate appearance compared to the more common variations. They have a lot of the same traits as other goldfish, they just look different.

These fish thrive in cold water aquariums since they have low natural temperature requirements (this can be as low as 50°F). A lot of the time you won’t even need heaters!

Fancy goldfish can generally get along with numerous other fish species and don’t demand excessive maintenance to sustain their health. However, there may be certain species-specific details you need to be aware of, but nothing extreme.

• Size: Species-dependant
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: Species dependant
• Water Temperature: Species dependant 

8. Mosquito Fish

This is a fascinating species that is often kept in ponds. However, some aquarists enthusiasts choose to keep them in tanks.

No matter what your personal preference is, we believe it would be unwise not to include them on our list.

Their fish stems from their aggressive consumption of insect larvae. This is why so many people think of them as one of the best pond fish. These fish will keep things bug-free!

Mosquito fish are extremely low-maintenance and quite hardy. They can adapt to almost all living conditions with ease. While they may show occasional aggressiveness, but that’s not very common behavior.

• Size: 3 inches
• Difficulty: Beginner
• Minimum Tank Size: 20 gallons
• Water Temperature: 65°F to 75°F

9. Bristlenose Pleco

This is one of the most popular species within the freshwater aquarium community and is an excellent option for cold water fish.

The Bristlenose Pleco has a very interesting appearance that you can’t ignore. Thy have a set of protruding appendages around their head and nose area, which explains why they are commonly known as the Bushy Nose Pleco.

Their versatility is one of the reasons why these fish are so popular. You can put them in almost any aquarium, with almost any other species. They can’t be bothered!

Among all the fish we recommend to our readers, this could be the species we endorse the most.

• Size: 3 to 5 inches
• Difficulty: Beginner
• Minimum Tank Size: 25 gallons
• Water Temperature: 60°F to 80°F

10. Rosy Red Minnow

Rosy Red Minnows are one of our preferred species, and are among the top choices fir cold water fish in your aquarium.

These fish can thrive in variety of different conditions because they are very. You can even use them as feeder fish if you so choose.

They can withstand water temperatures as low as 50°F which means you can keep them in tanks without a heater (if it complements the rest of your setup. They don’t require any specific habitat requirements, providing you with the flexibility to plan around their tank mates.

• Size: 2 to 3 inches

• Difficulty: Beginner
• Minimum Tank Size: 10 gallons
• Water Temperature: 50°F to 78°F

11. Asian Stone Catfish

These little critters are one of preferred freshwater catfish species to keep in cold-water tanks. They’re peaceful, hardy, and very easy to care for.

Their tiny size is plays a big role in what makes the Asian Stone Catfish so loved. This also makes them an excellent choice as a nano fish for small tanks.

These fish have an extremely interesting appearance that set them apart from other species. At times, they may be challenging to spot .Their bodies are highly textured, and they resemble being rendered by a bunch of polygons.

• Size: 1.25 inches
• Difficulty: Beginner
• Minimum Tank Size: 5-10 gallons
• Water Temperature: 64°F to 75°F

12. Celestial Pearl Danio

The Celestial Pearl Danio is a stunning species that many aquarists admire. Their interesting colors and pattern make them a great choice for anyone interested in bringing some color to their tank.

This species is also a good option if you prefer low-maintenance fish. Although there may be certain aspects of their maintenance that require some level of acquaintance, they are generally easy to maintain.

These fish are the best option for well-planted aquariums. The reason for that is not only because it is what they are accustomed to in their natural habitat, but also because it accentuates their colors.

We usually recommend this species to other aquarists. Unless you’re going for a very cold tank, there’s no reason not to give them a shot.

• Size: 1 inch
• Difficulty: Intermediate
• Minimum Tank Size: 10 gallons
• Water Temperature: 73°F to 79°F

13. One-Sided Livebearer

The ideal water parameters for this species are still a topic of debate, and as a result, they are not commonly in very many tanks.

But it’s clear is that they are a great cold water aquarium fish.

The One-Sided Livebearer is not complicated, they can do best in low temperatures. This species is easy to care for, hardy, and peaceful. However, it’s usually best to put them in a species-only tank.

Their name come from the fact that they always mate on one side. This behavior can be fascinating to watch, so if you’re a breeder you might be in for a treat!

• Size: 4 inches
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: 10-15 gallons
• Water Temperature: 64°F to 73°F

14. Pygmy Sunfish

The Pygmy Sunfish is a remarkably attractive species and is considered one of the best fish for cold water aquariums. Interestingly. This fish is not very well-known, even among those who want to keep fish without a heater.

Out of all the fish mentioned on this list, the Pygmy Sunfish stand out for its ability to handle low water temperatures. With a minimum of 45°F, making difficult to find another species with a similar ability to adapt.

Taking care of them is not very hard, and these fish tend to be quite lively as a result, they are an excellent choice for aquarium enthusiasts who seek a cold-water alternative that is not inactive.

We highly recommend doing some additional research on this species before you make a purchase. While they’re not overly hard, there are a few areas of care that you’ll need to be familiar with.

• Size: 1.25 inches
• Difficulty: Intermediate
• Minimum Tank Size: 5-10 gallons
• Water Temperature: 45°F to 80°F

15. Dojo Loach

We’ve been big fans of the dojo loach for a long time. This is quite a popular due its unique look and ease of care.

In our opinion, this fish is among the most entertaining to observe. They’re highly active and friendly, which means they are constantly engaged in some activity.

With their ability to thrive in low water temperatures down to 50°F, the Dojo Loach should be at the top of your list if you are interested in fish that don’t need heaters. They’ll be just fine!

It’s important to bear in mind that a slightly larger tank in necessary to keep them, unlike many of the other fish we have discussed that can be kept in smaller tanks. However, if space is not an issue, it is definitely worth considering keeping them.

• Size: 6 inches
• Difficulty: Beginner
• Minimum Tank Size: 55 gallons
• Water Temperature: 50°F to 82°F

16. Paradise Fish

This species is undeniably one of the most aesthetically-pleasing species on the list. Paradise Fish has captivated aquarists for years with its vibrant hues and flowing tails (ourselves included).

Caring for these fish is something that anyone can handle. As long as you devote some time to understand their main care needs and how to establish their living environment, you should be face no problems.

That being said, they may exhibit some aggression when placed in unfavorable circumstances or when housed with incompatible tank mates. However, this can be easily remedied by keeping them with tranquil fish that are too large to be bullied.

•  Size: 2.5 inches
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: 20 gallons
• Water Temperature: 68°F to 82°F

17. Rosy Barb

If you love the color red, you’ll admire this fish. This species boasts a vibrant hue that will introduce an entirely new level of visual dynamic to any aquarium they’re kept in

The Roxy Barb is a species that has amassed a loyal following of aquarists for a various reasons beyond their coloration. These fish are relatively undemanding, active, and peaceful.

This allows you to be flexible when it comes to the kind of habitat you want to put them in. When you combine this with their ability to handle cooler water they get even more appealing.

• Size: 6 inches
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: 30 gallons
• Water Temperature: 64°F to 72°F

18. Empire Gudgeon

The Empire Gudgeon possesses some of the most interesting fins. Making it truly unique species with few comparable counterpart.

In addition, they exhibit some neat colors. Despite its distinctive features, this species appears to be overlooked by the fishkeeping community.

Ironically, the majority of aquarists who are aware of this species are those who like keeping cold tanks. Even though the Empire Gudgeon can thrive in a diverse range of water temperatures.

• Size: 4.5 inches
• Difficulty: Intermediate
• Minimum Tank Size: 45 gallons
• Water Temperature: 59°F to 78°F

19. Least Killifish

This fish is particularly well-suited for aquariums with lower water temperatures, making it an ideal choice for those who wish to maintain such conditions. Additionally, the Empire Gudgeon is remarkably low-maintenance and an excellent option for individuals seeking a pet that doesn’t demand much of their time.

We’ve always said that this species bears a resemblance to slender Pea Puffer. With both species displaying similar color patterns and possessing a slender yet robust caudal peduncle.

Most of the aquarists we know have a ton of these fish in their aquarium. due to their peaceful nature and their small size, you can have them in large groups and with a wide variety of other species.

• Size: 1.5 inches for females, 0.75 inches for males
• Difficulty: Beginner
• Minimum Tank Size: 5 gallons
• Water Temperature: 66°F to 75°F

20. Gold Barb

Lot of aquarists tend to choose The Gold Barb for cold water aquariums due to its beautiful bright colors and hardy nature. This fish can brighten up even the dimmest aquariums with its vibrant yellow.

They’re a very easygoing and mellow fish can coexist harmoniously with plenty of other species as well. We recommend you to keep this fish in a school, so that’s why they can’t get away with super small tanks.

If have any interest in this fish you might have search before you find it in stock. Due to high demand, Gold Barbs can be a little tricky to find!

• Size: 3 inches
• Difficulty: Beginner
• Minimum Tank Size: 20 gallons
• Water Temperature: 64°F to 75°F

21. Medaka Ricefish

To be honest, most of the aquarists we talk to don’t are aware of this species. This species has two names, the Japanese Ricefish and the Medaka Ricefish.

There is an ongoing debate regarding whether this fish should be classified as a killifish or not, but no changes in its classification have been made yet. Regardless, the Medaka Ricefish is an excellent option for those seeking a peaceful species that can coexist with various other fish types. When observing them swimming with other species, they appear indifferent and scarcely notice their tankmates.

• Size: 1.5 inches
• Difficulty: Intermediate
• Minimum Tank Size: 15-20 gallons
• Water Temperature: 64°F to 75°F

22. Rainbow Goodeid

This is a very pretty fish that’s hard to find. Because of their critically endangered status can be a bit expensive and not in stock at most fish stores.

However, if you come across one they’re quite easy to keep. The Rainbow Goodeid is low-maintenance, hardy, easy to feed, and tolerant of a wide range of temperatures and parameters.

Given the perilous situation of this species’ population, it is crucial to exercise caution and conduct comprehensive research into their recommended habitat requirements before acquiring one as a pet.

• Size: 2 inches
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: 20-30 gallons
• Water Temperature: 67°F to 76°F

23. Axolotl

The Axolotl is an interesting creature that gained immense popularity over the last few years. While we’re featuring them on our list of the best cold water aquarium fish it is worth noting that it is technically a salamander.

It is also known as the Mexican Walking Fish, owing to its unique movement pattern around the water. While it does swim, you’ll also see them using their legs and arms to walk around the tank as well.

Despite being an extraordinary creature, the Axolotl is relatively easy to care for. They thrive in tanks without heaters and have simple care requirements, making them an excellent option for novice aquarists.

• Size: 8-18 inches
• Difficulty: Beginner
• Minimum Tank Size: 20 gallons
• Water Temperature: 57°F to 68°F

24. Rainbow Shiner

This is a species that’s captivating to look at. Living up to their name, the Rainbow Shiner is a mix of metallic and color glimmer.

Observing a group of Rainbow Shiners swimming around in an aquarium is a breathtaking experience, as they resemble dazzling little darts zipping through the water with their striking metallic shine.

Rainbow Shiners are highly active fish and are almost constantly in motion, adding to their allure and making their striking beauty even more captivating.

• Size: 3 inches
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: 20 gallons
• Water Temperature: 55°F to 75°F

25. Hillstream Loach

This species is one of the most distinctive fish on the list. With their cool flat built, this fish will stand out among almost any other species.

Hillstream Loaches Possess a low and flat body shape due to their native environment. These aquatic creatures spend their time in waters with rapid currents. And their body structure allows the fish to park themselves on a surface without exerting much effort to prevent themselves from being swept away.

Maintaining an appropriate water current is crucial for the well-being of Hillstream Loaches. Apart from simulating their native surroundings, it also facilitates the infusion of additional oxygen into the water, which is a vital requirement for this species.

• Size: 2-3 inches
• Difficulty: Intermediate-Expert
• Minimum Tank Size: 50 gallons
• Water Temperature: 68°F to 75°F

26. Clown Killifish

The Clown Killifish is a gorgeous species that has received a lot of attention in recent years. These tine creatures are very easy to maintain and don’t require a complicated tank setup in order to thrive.

With a minimum water temperature tolerance of 68°F, you can keep these in colder tanks without facing any issues. They’re very peaceful as well which permit you to match them with a variety of other species.

When they are young these fish tend to school together frequently, but as they mature, they tend to become more solitary in nature, which is an intriguing aspect of their behavior.

• Size: 1.5 inches
• Difficulty: Beginner-Intermediate
• Minimum Tank Size: 5 gallons
• Water Temperature: 68°F to 79°F

27. Zebra Danio

The Zebra Danio has a loyal following in the freshwater aquarium community. This is partly because they’re so pretty and partly due to their ease of care.

These are one of the most beginner-friendly fish out there. You can keep them in small and cold aquariums, and you don’t have to worry about their diet or interactions with other fish.

It’s an enjoyable experience to watch these fish swim around in a group. Their striking stripes ensure that they provide a remarkable spectacle whenever they move around the tank.

• Size: 2 inches
• Difficulty: Beginner
• Minimum Tank Size: 10 gallons
• Water Temperature: 64°F to 74°F

Closing Thoughts

As you can see, several fish can thrive in cold water aquariums. Some of which are quite popular, and others remain relatively unknown.

The idea of keeping a fish that doesn’t need a heater might seem weird at first. After all, most of the common freshwater fish need one!

But once you overcome the initial unfamiliarity it’s quite a luxury! It only saves you money, but also provides an opportunity to create a more natural aquarium setup.

If you know of any cold water fish that we have not included in this list, please feel free to share your suggestions with us. We are always striving to make our guides as informative and helpful as possible, and appreciate any input that can help us achieve this goal.