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? We’ll be covering 10 more coldwater species in this article. Goldfish is one of the most well-known aquarium fish.

1. Sunset Variatus Platy

Livebearers, or fish that bear young, have a special place within our hearts. However, we love the ease with which they produce baby fish. The sunset variatus platy (Xiphophorus variatus), has been one of our favorite fish over the years. They combine all the things you would want in a perfect fish:

– Available in a huge variety of colors and patterns – Very hardy and inexpensive – Only two to three inches long – Lively yet gets along with other fish and plants – Easy to breed for fun

They can live in a broad range of temperatures, with or without a heater, and they tend to prefer pH levels above 7.0. They will love to be mixed with the other fish listed on this page.

Variatus platies come in a huge variety of colors and patterns and are very fun to breed.

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 between 6.8 and 8.0, moderate water hardness, as well as cooler waters. It is also known by the Danio margaritatus, CPD or galaxy rasbora. However, given the right environment, you can often find the males circling each other in a dance off competition. If you keep them in a group of six or more, they will make a spectacular display for your planted tank.

Celestial pearl danios look stunning in a planted tank and are often used by aquascapers to highlight their designs.

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. They should be kept in a group of six or more because they are expensive and difficult to find. If you have the money and are willing to wait for them to mature, they will be the most beautiful fish you have ever seen.

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

Do you need an algae eater to heat your tank? 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 varieties of similar loaches like the Chinese hillstream and butterfly loach. Most of them prefer cooler waters with a pH of 6.6 to 7.8. Besides snacking on algae, hillstream loaches love to eat Repashy gel food, good quality wafers, and other foods that sink to the bottom of the aquarium. You may notice some breeding behavior if you feed them properly, and you will see baby aliens popping up all around the aquarium.

Hillstream loaches can be a little aggressive with one another, so either get one loach by itself or at least three in a group to spread out any territorial or breeding behavior.

5. Endler’s Livebearer

Poecilia wingei is like a smaller version of its famous cousin, the guppy, because it also has been bred to display many unique colors and fin shapes. The original wild-type Endler’s Livebearer is the best choice. They can survive at room temperatures with a pH range from 6.5 to 8.5. They are peaceful and blend well with other fish in the aquarium. To breed them, just set up a 10-gallon tank with approximately two males and four females. Fill the aquarium with live plants and lots of hiding spots, and soon you have a factory of life, bursting at the seams with fish babies.

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

6. Clown Killifish

Another coldwater nano fish, the Epiplatys Annulatus killifish, can be kept together with small species in a community tank. Their eyes are strikingly blue and they have vertical stripes on their bodies. The males have a tail that looks like it is a rocket flame, hence their nickname “rocketkillifish”. Like many killifish, they tend to swim at the top of the tank, so make sure your aquarium has a tight-fitting lid to prevent them from jumping out. Clown killifish prefer a pH of 6.5 to 7.8 with moderate water hardness, and they will readily lay eggs in floating plants or a spawning mop.

Clown killifish can live up to three years if they are well taken care of.

7. Cherry Shrimp

Neocaridina davidi, also known as Neocaridina davidi, are very popular among fish keepers due to their bright colors that look like Skittles, love for eating algae and leftover fish foods, and easy breeding (even outdoors in cold weather). You can easily purchase them at your local fish store or aquarium society auction, and sometimes even major pet store chains will carry them. You can get 10-20 shrimp to fill a 10-gallon aquarium. Once they are established, ensure that the water has enough calcium and minerals. Before long, you will have a swarm of dwarf shrimp. For more information, check out our full care guide here.

Neocaridina shrimp were originally brownish-gray in appearance, but now they’ve been bred into many colors, such as red, yellow, blue, orange, green, and black.

8. Dojo Loach

Are you looking for something larger? Consider the dojo loach (also known as the weather loach or Misgurnus anguillicaudatus). The dojo loach is a hot dog-sized fish that can grow to 10-12 inches in length. It should be kept separate from smaller species, such as celestial pearl daanio and cherry shrimp. Try the variatus platy and barbs instead. These fish are not edible. Dojo loaches display many fun behaviors, such as scavenging for food with their whisker-covered mouths or burrowing into the gravel. They are very affordable and will make a wonderful addition to any coldwater aquarium.

Dojo loaches often find their way into goldfish tanks thanks to their tranquil temperament and preference for cool water.


9. Barbs

Many barbs are great in cooler waters but often have the reputation for being fin nippers, so keep them in groups of six or more to minimize their aggression. 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. Barbodes semifasciolatus, the gold barb, is slightly more aggressive than the rosy bar. They would be able to live with dojo loaches and other barb species. They can grow up to three inches and should be kept in a tank of 29 gallons or more. Their large appetites make them quite entertaining to feed.

Barbs can swim very fast and should be kept with six other people to reduce aggression.

10. White Cloud Mountain Minnow

Tanichthys Albonubes can be purchased as a feeder fish in pet shops, but they also make excellent beginner pets due to their ability to survive in nearly any tank size and temperature (aslong as it is not too hot). Because of their affordable price, these minnows have been called the “poor man’s neon Tetras”. They are available in many different varieties such as long-finned, golden, and albino. You can get a group of 10-12 fish and breed them for fun.

Many people raise these tough minnows outdoors in large plastic tubs during warmer summer months.

If you enjoy articles like this, check out our Top 10 lists for more fish and plant stocking ideas!