10 Best Coldwater Fish that Don’t Need A Heater

10 Best Coldwater Fish That Don’t Need a Heater

Most freshwater pet fish require an aquarium heater because they’re used to tropical temperatures, but did you know there’s a whole class of coldwater fish that are perfectly fine at room temperature? Goldfish are the most well-known coldwater fish in the aquarium hobby, so in this article, we’re going to cover 10 more cool species that can live without a heater.

1. Sunset Variatus Platy

Because they are so easy to make baby fish, livebearers hold a special place for us. But, over time, the sunset variatus plate (Xiphophorus variatus), is one of our favourites. They have everything you could want in a fish:

You can find them in many colors and patterns.

They can live in a broad range of temperatures, with or without a heater, and they tend to prefer pH levels above 7.0. You’ll fall in love with them when you mix them with other fish and live plants.

Variatus platies are fun to breed and come in many colors and patterns.

2. Celestial Pearl Danio

Because of its tiny size and bright red-orange fins, this nano fish is very popular in aquascaping. It can tolerate pH ranges from 6.8 to 8.8, moderate water hardness, and cooler waters. It is also known as the Danio margaritatus or the galaxy rasbora. The males can dance off each other if they are in the right environment. Keep them in a school of six or more, and you’ll have a stunning display for your planted tank.

Celestial danios are stunning in a plant tank and are often used as accents by aquascapers.

3. Rainbow Shiner

Rainbow shiner (or Notropis Chrosomus, a native to the United States) is used to cooler waters. They are known for their brilliant purple and pink spangling, especially during mating seasons. These torpedo-shaped fish grow to 3 to 3.5 inches long and can be kept with other peaceful fish that enjoy similar water parameters. It is best to keep them in a small school of six or greater, as they can be expensive and difficultly source. You’ll get the best-colored fish if you have the finances and can wait one year for them mature.

This United States native fish is hard to find but well-worth the cost because of their unusual purple and pink coloration.

4. Hillstream Loach

Are you looking for an algae eater? You don’t need to look any further. The hillstream locach (Sewellia liolata) is not only an excellent eater of brown diatoms green algae but it also looks very unusual. It can be seen sucking on the side glass of your glass like an alien stingray. There are many types of similar loaches such as the Chinese hillstream loach and the butterfly loach. They prefer cooler water and pH levels between 6.6 and 7.8. Hillstream loaches enjoy eating Repashy gel food and good quality wafers. If you feed them well, you may see some breeding behavior, and baby aliens will start popping up all over the place.

Hillstream loaches are a bit aggressive and can get a little territorial with each other.

5. Endler’s Livebearer

Poecilia Wingei looks like a miniature version of the famous guppy. However, it has been bred with many different colors and fin shapes. However, if you get the original, wild-type Endler’s livebearer, they are very hardy and can live at room temperature with a wide range of pH from 6.5 to 8.5. They’re peaceful and can be mixed with most of the fish on this page. A 10-gallon tank can be used to breed them. It should contain approximately two males as well as four females. The aquarium should be filled with live plants. There should also be plenty of hiding places. Soon, you’ll have a factory full of fish babies.

Endler’s livebearers can be very prolific and will readily breed in a planted tank with lots of cover.


6. Clown Killifish

This killifish (Epiplatys annulatus) is another coldwater nano fish that can be kept in a community tank with other small species. Their striking blue eyes are accentuated by their vertical markings and their tails resemble rocket flames, which is why they are called “rocketkillifish”. They swim high up in tanks, and like many other killifish, will often jump out of aquariums. Clown killifish like a pH between 6.5 and 7.8 with moderate water hardness. They will lay eggs in floating plants, or a spawning mop.

Unlike some killifish, clown killifish are not an annual species and can live about three years or more if well cared for.

7. Cherry Shrimp

Neocaridina davidi are very popular among fish keepers because of their bright, Skittles-like colors, fondness for eating algae and leftover fish food, and ease of breeding (even outside in cold weather). These fish can be bought at your local aquarium society auction and some pet shops chains. Start with 10 to 20 shrimp for a 10-gallon aquarium, make sure they have enough calcium and minerals in their water, and soon you’ll be overrun with beautiful dwarf shrimp. Our complete care guide is available here.

Neocaridina Shrimp were initially brownish-gray. However, they are now available in many colors including red, yellow, orange, green and black.

8. Dojo Loach

Are you looking for something larger? The dojo loach, also known as the Misgurnus Anguillicaudatus or the weather loach, is a good choice. The hot-dog-sized fish can reach 10-12 inches in length and should not be kept alongside smaller species such as the celestial Pearl danio or cherry shrimp. Try the variatus platy and barbs instead. These fish are not edible. Dojo loaches are known for their playful behaviors such as digging into the gravel or scouring for food with their whisker-covered faces. They are quite affordable for their size and would make a great addition any large, coldwater aquarium.

Dojo loaches are often found in goldfish tanks because of their peaceful temperament and matching preference for cooler water.

9. Barbs

While barbs love cooler waters, many have the reputation of being aggressive and can bite. There are many types of the rosy barb (Pethia Conchonius), including neon, long-finned, and normal. They can swim very quickly and are relatively peaceful so you can keep them alongside other community fish of similar size. The gold barb (Barbodes semifasciolatus) is a little more aggressive than the rosy barb, so they would do well with other barb species and dojo loaches. Both species grow to approximately three inches or more, should be kept in a 29-gallon or larger tank, and are quite entertaining to feed because of their hearty appetites.

Barbs are very fast swimmers and should be kept in a school of six or more to lessen any aggression.

10. White Cloud Mountain Minnow

Tanichthys albonubes are often sold at pet shops as a feeder fish. However, they are great for beginners because of their resilience and ability to survive in any size tank. These minnows are sometimes called “the poor man’s neon tetras” due to their low price. However, they can be found in many varieties, including albino, long-finned, and golden. For fun, get 10-12 fish, and enjoy their simple beauty.

Many people keep these hardy minnows in plastic tubs outdoors during the warm summer months.

You might enjoy these articles. Check out our Top 10 lists to see more ideas for stocking fish and plants.