10 Best Coldwater Fish that Don’t Need A Heater

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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? The most popular coldwater fish in aquarium hobby is the goldfish. In this article we will cover 10 other cool species that can survive without heaters.

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:

It is available in a variety of colors and patterns. – They are very hardy and affordable. – About two to three inches in length. – Friendly and gets along well with other fish and plants. – Easy to breed for enjoyment

They can survive in all temperatures. Mix them with live plants and other fish on this list, and you’re sure to fall in love with them!

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

2. Celestial Pearl Danio

This nano fish is quite popular in the aquascaping world because its golden spots and red-orange fins make it look like a tiny brook trout. It can tolerate pH between 6.8 and 8.0, moderate water hardness, as well as cooler waters. It is also known as the Danio margaritatus or the galaxy rasbora. However, given the right environment, you can often find the males circling each other in a dance off competition. 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

As a native of the United States, the rainbow shiner (or Notropis chrosomus) is definitely used to cooler waters and is known for its brilliant purple and pink spangling, especially during mating season. These fish are torpedo-shaped and can grow up to 3 to 3.5 inches in length. They can be kept with peaceful fish that have similar water conditions. 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.

These native fish from the United States are hard to find, but worth it for their unique purple and pink colors.


4. Hillstream Loach

Need an algae eater for your unheated tank? You don’t need to look any further. The hillstream loach (Sewellia lineolata) not only does an amazing job of munching on brown diatoms and green algae, but it also looks fairly unusual, like a miniature alien stingray sucking on the side of your glass. 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. Hillstream loaches are fond of eating Repashy gel food, high quality wafers and other foods that sink to bottom of 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. 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

The killifish (Epiplatys anulatus) can also be kept in a tank together with other small fish. Their striking blue eyes are accentuated by their vertical markings and their tails resemble rocket flames, which is why they are called “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 pH 6.5 to 7.8 and moderate water hardness. They will lay eggs in floating plants or on a spawning mat.

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

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). They can be purchased at any local aquarium society auction or fish shop. Sometimes, even major chain pet stores will have them. For a 10 gallon aquarium, you can start with 10-20 shrimp. Make sure that they have enough calcium and other minerals. Soon, your tank will be filled with dwarf shrimp. Our complete care guide is available here.

Neocaridina shrimp are originally brownish-gray, but they have been bred to many colors such as red, yellow and orange.

8. Dojo Loach

You are looking for something bigger? You might be interested in the dojo locach (also called the Misgurnus anguillicaudatus) This hot dog-sized fish can reach 10 to 12 inches long and therefore should not be kept with smaller species on this list, such as the celestial pearl danio or cherry shrimp. You can instead try varitus platy, barbs and other medium-sized fish that aren’t considered food. Dojo loaches display many fun behaviors, such as scavenging for food with their whisker-covered mouths or burrowing into the gravel. 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

Although barbs can be great in cooler water, they are often known for their aggressive nature. Keep them in groups of six to eight to reduce 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. 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. 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.

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