What you need to know

Coldwater Fish Tank

Josie F. Turner
By Josie F. Turner, Journalist specialized in Animal Welfare. Updated: January 1, 2019
Coldwater Fish Tank

There is a very good option for those people who love the animal world but do not have much time to devote to it: having a cold water fish tank.

Due to the small amount of time people tend to spend at home nowadays, most of us do not have time to care for a cat, let alone a dog. Fish are animals that require very little care and delight us with a vision of beauty when we watch them swim. Fish tanks do not require constant attention: fish eat and live quietly in their space. Even so, we must have some basic knowledge to ensure that our fish develop well in their environment. That's why today, we will explain the main guidelines for cold water fish tank care.

You may also be interested in: 9 Fish for an Outdoor Pond
  1. About cold water fish
  2. Needs of cold water fish
  3. Goldfish
  4. White Cloud Mountain Minnow
  5. Koi
  6. Bubble Eye
  7. Telescope goldfish

About cold water fish

Cold water fish keep perfectly in room temperature tank water and withstand (within normal parameters) the oscillations that the seasons produce in the water´s temperature. This is the main characteristic that distinguishes them from tropical water fish, which require strict water monitoring. That is why cold water fish tanks are much easier to maintain and care for.

In general cold water fish withstand temperatures oscillating between 16 and 24 ° C. There are some specific species such as the Dojo Loach fish that will withstand a maximum of 3°C, so we need to get detailed information for each type. In general, cold water fish are very resistant thanks to the fact that many of them have methods to adapt to extreme situations based on their physical characteristics.

Cold water fish are very diverse because of the mutations and controlled reproduction carried out by the breeders. We can find them in a variety of colors, sizes and fin shapes.

Finally, a few things to keep in mind:

  • Fish who live in the same tank eat and swim together (they are not isolated), isolation or lack of appetite can warn us of a disease or problem.
  • We must always ask the experts regarding the compatibilities between different species before releasing them into the same space. Failure to do so may involve the death of one or more fish.
  • Fights between different fish (of the same or different species) when this should not happen according to the breed, may mean that one of the fish in question has a disease. It would be advisable to isolate it from the rest of the fish for its recovery.
  • Fish scales reveal their health; if we see dramatic or unusual changes we will also isolate the fish from the group.
Coldwater Fish Tank - About cold water fish

Needs of cold water fish

First of all, we will set the cold water fish tank temperature to about 64° F and pH7. In specialist shops we will find a variety of test equipment to check that the fish tank water levels and its components are correct.

It is very important to install a filter in the aquarium as water renewal is necessary (more than in the case of tropical fish). For cold water fish aquariums we recommend a power filter as both its maintenance and installment are easy to carry out and they do not interfere with the decoration of the aquarium. Having the filter requires us to change 25% of the water every one or two weeks.

It is advisable to put 3 to 5 cm of gravel at the bottom of the tank and preferably choose artificial decoration as not only does it not need changing but it also stops the fish from eating plants and natural algae, some of which are not good for them.

We can also add decorations of all types and sizes (as long as the fish have room to swim). We recommend prior cleaning in boiled water.

Being cold water fish, they will not need heaters to keep the fish tank water at a particular temperature, but we can still place a thermometer in the tank to get more detail about the daily lives of our fish.


The Goldfish is a cold water fish descendant of the common carp. It comes from East Asia. Contrary to what many believe, the orange Goldfish is not the only cold-water fish from this species as there are others in different colors and shapes. Because it requires a lot of oxygen, it is recommended for them to live in a tank that is as large as possible, and with at least one companion.

They need specific feeds and rations that are easily available for purchase. By applying the basic rules mentioned in this small section, you can make sure that your Goldfish lives a healthy life ranging between 6 and 8 years. Discover how to care for a goldfish and find out why they can be aggressive on AnimalWised.

Coldwater Fish Tank - Goldfish

White Cloud Mountain Minnow

Originating from the mountains of Baiyun (White Mountain) in Hong Kong, this small cold water fish called White Cloud Mountain Minnow dazzles with its bright and bold colors. They are approximately 4 to 6 centimeters long and have a greenish brown color with a yellow-pinkish line and yellow and red fins.

They are hardy fish that normally live in groups of 7 or more individuals of the same species. In general they get along with other fish such as Goldfish, so they allow you to have a varied and striking cold water fish tank.

These cold water fish are very popular and easily available due to their easy care. They take food of all kinds as long as it is small, and they require a temperature of between 15 and 20 degrees, ideal for a home. They do not usually have diseases or problems, which makes life easy for the owners.

The only thing we must be careful about with this species is that they are very used to 'jumping'. We must therefore always keep the cold water fish tank covered.

Coldwater Fish Tank - White Cloud Mountain Minnow


Koi are cold water fish relative of the common carp. Although they are native to China, they were made world famous by the Japanese, and they live on every continent except Antarctica.

“Koi” can translated as 'affection' or even 'love'. The farming of this type of cold water ornamental carp flourished in China during the King Dynasty and in Japan during the Yayoi era. In Asia it is believed that this type of cold water fish brings good luck.

Koi is the most popular pond fish thanks to its physical strength, and we can find them easily in any fish specialist store. They can reach 2 meters in length, although usually they grow up to 1.5 meters in large ponds (up to 70 cm in large aquariums). They present different colors, bright and unique in each individual. By using selective breeding, fantastic specimens are produced; these can be valued up to $100,000.

Koi is an excellent cold water fish as there is little complexity in its care. It coexists beautifully with other specimens of its size, but we must be careful because they feed on other species of smaller fish. Koi also feeds on small invertebrates, algae, cold water crustaceans etc. We can supply them with daily 'flake food' specifically made for medium and large fish, as well as other more specific elements, so that their diet is varied.

The life expectancy of koi carp is estimated at 25 to 30 years, but they can live much longer in favorable conditions.

Coldwater Fish Tank - Koi

Bubble Eye

The Bubble Eye fish is a cold water fish native to China; it comes from the Goldfish. Their eye area has a peculiar shape that gives them a unique look. It is called “bubble eye” because it has bubbles: huge fluid-filled sacks where their eyes rest, always looking up. The bags can explode easily if rubbed with other fish or elements in their environment. We do not need to worry if that happens because they usually grow back. The bubble eye is therefore considered a solitary cold water fish.

Normally, they are between 8 and 15 cm long, and swim slowly and thoughtfully. It is recommended that they live alone or with others of the same species in order to avoid malnutrition or attacks. Also, their habitat should be free of trunks and elements that could hurt the eyes (it can have natural vegetation). It adapts perfectly to cold water.

This cold water fish can be of various colors such as blue, red, chocolate, etc. We must supply food near where it is so that it notices it. It eats voraciously and adapts easily to different types of food such as flake based food, mushy food, parasites etc., as long as we leave it within its scope.

Coldwater Fish Tank - Bubble Eye

Telescope goldfish

The Telescope goldfish is a cold water fish variety that comes from China. Its main physical characteristics are the eyes that protrude from its head, giving it a unique appearance. The black telescope is also known as black moors for its full blackish and velvety appearance. We can find them in all colors and varieties.

These cold water fish require large and spacious aquariums, but they can never live in ponds (except for the black moor), as they could die if subjected to very low temperatures. As with the bubble eye, we should not keep pointy or sharp elements in the cold water fish tank as they could damage their eyes. The last thing to consider when creating a cold water fish tank for telescope goldfish is to ensure that the filters do not create excessive movements in the waters as this could destabilize the fish.

They are omnivorous fish that must eat small amounts of food divided in various feeds during the day. It is recommended that you vary food often to avoid bladder problems. We can feed them different products that are available on the market.

Keep in mind that telescope goldfish life expectancy is of around 5 to 10 years.

Coldwater Fish Tank - Telescope goldfish

If you want to read similar articles to Coldwater Fish Tank, we recommend you visit our What you need to know category.

Write a comment
Add an image
Click to attach a photo related to your comment
What did you think of this article?
1 of 7
Coldwater Fish Tank