Best Cold Water Aquarium Fish (20 Options!)

When it comes to cold water aquarium fish, many different species of aquatic life can make a great addition to your fish tank regardless of the tank size. From tiny Pygmy Sunfish to larger Fancy Goldfish, here is a list of some of our favorite cold water aquarium fish that you can keep without an aquarium heater! In this guide, we’ll give you an introduction to the fish, and how you can care for them in your home environment.

What is a Cold Water Tank?

A cold water tank is an aquarium that contains fish and other aquatic animals adapted to living in colder temperatures between 45 and 68 degrees Fahrenheit. Coldwater tanks are generally easier to maintain than tropical tanks and less expensive for the novice aquarist to set up.

What Tank Size is Best?

Before you select your fish, it is important to determine what tank size best suits the species. For most cold water aquarium fish, a 20-gallon tank with plenty of live plants and decorations is the ideal size. For larger species, you may need to consider a bigger tank.

Cold Water Fish: Care Tips

Our Favorite Cold Water Fish

Cold water fish list with pictures

Hillstream Loach

These unique, bottom-dwelling fish are an interesting addition to cold water aquariums. They prefer temperatures between 68-75 degrees Fahrenheit and a slightly acidic pH level of 6.5-7.5. It’s important to provide plenty of hiding places, and we recommend keeping them in a tank with plants as these fish love to rest on them. You’ll often find these coldwater fish eating algae on the side of your tank – a great part of the clean-up crew for your cold water fish tank!

Pygmy Sunfish

Given their small size, your tank size can also be appropriately small. This fish species will eat a wide range of frozen or prepared foods. While not always the case in North American fish, they tend to live in acidic conditions, though this is not the case for all subspecies. If you live in the US, you may naturally find them in outdoor ponds!

The Pygmy Sunfish will be a great addition to your community tanks – we highly recommend them!

Cherry Barb

When housing these fish, it’s best to keep them in groups of at least six so they don’t become territorial. Remember, you’ll need an appropriate tank size as these fish can reach between 2-3 inches.

Koi Fish

We would rank Koi fish among the more difficult coldwater fish to care for, but that is related to their need for a larger tank or even an outdoor pond. If you have the space and are looking for a great addition to your cold water tank, koi are an excellent choice.

Guppy

These active fish are a great choice for those who want to add some movement and life to their aquarium. They can tolerate temperatures from 68-80 degrees Fahrenheit and pH levels between 6.5-7.8. When it comes to tankmates, guppies can be kept with other peaceful fish such as neon tetras or mollies. Guppies are almost always in stock at fish stores and generally make for a very popular small fish species. While they can also be comfortable in warm water, guppies (even the feeder fish) are quite resilient.

Try keeping Guppies with other community tank members like the Pygmy Sunfish, Rosy Barb, Celestial Pearl Danio, Clown Killifish, Paradise Fish, Rainbow shiner, or even Betta fish depending on the tank! Trying out a shrimp tank? Guppies can be great little fish for eating mosquito larvae.

Endler’s Livebearer

These peaceful, schooling fish are perfect for beginners who want to add some variety and color to their tanks. Endler’s are related to guppies, but be careful keeping them as tank mates if you don’t want them to crossbreed. It’s important to provide plenty of hiding places when you keep these fish with other tankmates, as they can become stressed if overcrowded or chased by other species.

Buenos Aires Tetra

These peaceful fish are best kept in small groups of five or more and thrive in temperatures between 65-75 degrees Fahrenheit. To keep these fish healthy, ensure the aquarium has plenty of swimming space as well as hiding places among rocks and plants. These cold water fish are easily cared for in an aquarium, but given their schooling nature do best when in the proper tank size. You should be able to easily find them at a local fish store!

White Cloud Mountain Minnows

This schooling species is a great fit for cold water tanks, as they prefer temperatures between 64-72 degrees Fahrenheit. Sometimes confused with bait fish, white cloud mountain minnows are an extremely popular cold water fish given their ability to easily breed and live with other hardy fish. Keep this species in a group of five or more in an aquarium with a proper tank size to ensure plenty of swimming room and hiding places.

Cherry Shrimp

While not a cold water fish, these invertebrates will be a great fit for your cold water fish tanks! Not only are these tiny shrimp colorful and fun, but their cleaning abilities make them great additions to most cold water tanks. While mosquito larvae can be an issue in some shrimp tanks, most fish keepers don’t have an issue when they keep their shrimp with compatible fish.

Goldfish

A classic cold water fish choice, goldfish can be great fun to watch as they explore the tank. Keep in mind that these fish will grow quite large and need plenty of swimming room, so make sure you have a large tank size. People often underestimate the tank size they need when keeping goldfish!

Goldfish prefer a temperature range cooler than tropical fish, but it does depend on the specific species. Keep in mind they produce a lot of fish waste, and these little fish won’t stay little for long!

All that said, you’ll easily find goldfish at most fish stores, and these make for a fantastic cold water fish. They are a top choice for fish keepers in outdoor ponds and a cold freshwater aquariums.

Fancy goldfish are the favorite of many coldwater fish keepers and should do well with other medium sized fish. Just make sure to keep them in the appropriately large tank size.

Dojo Loach

Like the Hillstream Loach, these bottom-dwelling fish are an interesting addition to cold water aquariums. Dojo loaches are known to be very fun to watch, and they don’t need an aquarium heater with a temperature range of 50 – 78 degrees Fahrenheit – and they even have been known to be in warm water aquariums. Make sure your fish tank has plenty of space for them to hide (we always are worried about tank size!) and room for them to swim.

Sunset Variatus Platy

Who doesn’t love livebearers? Platies are popular tropical fish that will make great members of a community tank with a wide range of tank mates. They can be kept in both warm water or a cold water fish tank, and can live with a wide range of other fish like betta fish, clown killifish, rosy bard, rainbow shiner, and more!

These great cold water fish are very hardy and don’t cost much, and you can find them in a wide range of colors. In all my years of fish keeping, platies have been some of the most fun to keep. One of the best parts of these very hardy fish is their ability to live in aquariums with many different tank size.

Another selling point – they have a wide range of appropriate water temperatures, which will allow you many options when it comes to other fish.

Boesemani Rainbowfish

This elegant species is one of the most popular community aquarium fish. They do best in slightly acidic water (6.5-7) and temperatures from 68-78 degrees Fahrenheit, meaning they are right on the edge of the acceptable water temperature for some others on the list. To keep them healthy, it’s important to provide plenty of open swimming space as well as hiding spots for when they feel stressed or threatened.

Celestial Pearl Danio

These small, active fish are a great addition to any cold water aquarium and don’t require a large tank size. They can live in a fairly wide range of water temperatures (69 – 79 F, so they make for a great cold water fish species that can be kept with other cold water fish or warm water aquarium fish.

With beautiful coloration, these near nano fish are a great choice if you are keeping coldwater fish.

Rosy Barb

This peaceful fish is an interesting addition to any cold water aquarium. They prefer temperatures between 64-72 degrees Fahrenheit and do best in groups of five or more. Provide plenty of swimming room and hiding places for this species to keep them healthy and active.

Neon Tetra

These vibrant little tropical fish are perfect for beginners who want to keep their tanks colorful and interesting. They prefer an acidic pH level between 6-7 and temperatures from 75-80 degrees Fahrenheit. If you plan on keeping these fish together, make sure they have plenty of hiding places and be careful not to overcrowd them (2-3 per gallon). While they are best known as tropical fish in community tanks, Neon Tetras can still withstand cooler water temperatures.

Axolotl

Well, these definitely aren’t nano fish! Axolotls are actually amphibians, but they are loved by many fish enthusiasts. The minimum tank size for these beautiful creatures should be 20 gallons. We recommend you check out our friends at Modest Fish to learn more: https://modestfish.com/axolotl-care/

Clown Killifish

These small, colorful fish are a great fit for cold water tanks. They thrive in a variety of cool water temperatures with other community tank members. Clown Killifish are known to swim near the top of the tank, so make sure you have a lid in place in case they jump!

These are one of the most beautiful fish you can add to a coldwater tank, though in our experience are sometimes difficult to find locally.

Zebra Danio

The Zebra Danio is an incredibly popular cold water fish, and it’s no question why. They are very hardy and can thrive in small or large tank size, and prefer water temperatures in the 64-72 degrees Fahrenheit range. These colorful, schooling fish are a great choice for a cold water tank. Keep these fish in a group of five or more in an aquarium with plenty of swimming room and hiding places for them to rest.

Gold Barb

The Gold Barb is a good cold water, small fish option that you’ll enjoy having in your tank. They prefer temperatures between 65-75 degrees Fahrenheit and do best in an aquarium with plenty of swimming space and areas to hide. They are becoming increasingly rare as wild caught fish though, so try to find them captive bred in the appropriate water temperature if possible!

Conclusion

Cold water aquarium fish are some of the most fun to keep, and there is such a wide range of appropriate tank sizes for you to choose from. When setting up a cold water aquarium, it’s important to consider the various needs of each species and the compatibility between fish. It’s best to choose species with similar temperature, space, and pH requirements when possible. Keeping these factors in mind will ensure that all of your fish stay healthy.

Also, it’s important to make sure your tank is properly maintained and free of toxins that could harm the fish. Regular water changes are essential for maintaining ideal water conditions as well as providing fresh oxygen for the fish. When you bring in new fish, make sure to inspect your tank regularly for any signs of disease or illness such as discoloration or loss of appetite.

We hope you enjoyed this post! Let us know if you have any questions in the Facebook group.