Having an aquarium is a way to have pets or animals for those people who cannot afford great care, as they require other animals. However, this does not mean we have to have the fish neglected.

cold water fish

Basic Need of Coldwater Fish

Although cold-water fish do not need constant attention, like other pets, they do need primary care for themselves and the aquarium where they will be. 

Therefore, when reading the description of each fish, you will see that the water in the aquarium should be around 18-20ºC, as well as a pH of approximately 7.

It is also important that the aquarium has a filter to renew the water and have the aquarium in optimal conditions. Therefore, it is necessary to change some water every week and a half. 

In addition, we advise you to include some decoration, sand, or artificial plants so that the fish sit in their habitat. Of course, you always have to respect the space these fish need to swim.

You need about 20 or 30 liters of cold water per fish. They have to be tanks of adequate size, which will vary depending on the fish that we put inside them. 

It cannot be the same size if one fish is going to live as if four will live. In addition, you have to consider that the fish grow, so even if you target them when they are small, you think that they will increase in size.

If several cold-water fish share the same aquarium, you should pay attention that they do not compete with each other, that they have enough space, and that they do not always eat the same food. Also, you will need to clean the water more often because the water will get dirty faster.

Having a varied aquarium with different fish can be very attractive. But there are times when the fish are not all at ease together. Observe how they live, eat and swim together to see that they can share a house.

The Goldfish

This fish, also known as Red Carp, is one of the most popular. It has become the best seller to be the favorite pet in the world of fish. Also, indeed, when you think of him, you imagine him orange. 

However, it is not the only tonality of this fish since you can find them with yellow, red, or white tones. This fish belongs to the carp family, which includes the largest fish in the world.

It is a small fish, but it can reach a size of between 10 and 20 centimeters if the conditions are right for it. As we have said, it is a cold-water fish, although its advantage is that it tolerates a rise in water temperature well. 


Its body is long and narrow, with the fins, two ventral and two pectoral, short and rounded.

As for its diet, it is omnivorous. This has the advantage that their diet can be varied, from dry food that you can buy in stores, also live or flake food. So what is essential is not to overfeed them, that is, to feed them once or twice a day and the amount indicated.

In the aquarium, you will have to keep it at a temperature between 20 and 30º, although it can withstand lower temperatures. As for the pH, the appropriate one is from 6 to 8.5.

Koi Carp

Like the previous one, this fish is also a variety of the common carp. It is a species you have undoubtedly seen in the park ponds of any city since it is widespread for them to be there. 

However, it is also ideally suited to large aquariums. It has to be significant because it can reach a meter and a half in length.

The diet is similar to that of the Goldfish. It is also an omnivorous fish that eats invertebrate foods and algae, insects, or zooplankton. But they can be supplied with commercial food, as in the previous case.

koi fish or Koi Carp Fish

To keep this pet, the temperature has to be around 20ºC, although it resists less and more temperature, and the pH should be about 7.

Telescope Fish

This fish has a unique appearance. Its bulging eyes protrude from the body and, therefore, it is also known as dragon eyes. Its body is round and short. It is not a large fish. Its large tail fin with rounded tips also stands out. A curiosity is that its vision is not the most adequate despite being called a telescope. His vision is limited, and over the years, it is lost.

Unlike the two cold-water fish, it cannot live in a pond since it could die at low temperatures. But, again, we face an omnivorous pet, so its diet will be similar and straightforward.

Telescope Fish or Globe eye goldfish

The aquarium needs a water temperature of between 18º and 23ºC, which is quite similar to the previous ones. The pH is also identical, between 7 and 7.5

Chinese Neon

If you decide to have this fish with any of those named above, you will have a very diverse aquarium in size since this animal is much smaller, measuring between 4 and 6 centimeters. 

However, your aquarium will have bright and striking colors, as its greenish-brown color is mixed with memorable yellow lines and fins of the same tones.

We advise you that if you decide to put this fish in the aquarium, do it with more than one of its species since they are used to living in groups. Also, you should know that it gets along well with Goldfish. 

Chinese Neon Fish

What you should keep in mind is the type of fish tank. They are cold-water fish that can surprise you since they can escape and get out of the water with a jump. Therefore, it will be appropriate to have a lid.

Its diet is the same, omnivore. Their food varied but smaller quantities due to its size. The water may have a temperature between 15 and 20 degrees and a pH between 6 and 8. Remember to keep the aquarium clean.

Sun Perch

Sun Perch

If you want a fantastic aquarium, the Sun Perch is one of the best options. His body mixes different colors by zones. Orange and yellow in the vertebral area and bluish and greenish on the sides. It is not a large fish, but it does reach 20 centimeters.

Its diet is perhaps the most varied, being mainly carnivorous fish. It feeds on small fish, insects. However, it also accepts dry or frozen food. 

It may not be an excellent option to put it in the same aquarium since they can become territorial, especially during the breeding season. As for the aquarium conditions, they tolerate from low temperatures, 4ºC, to 25ºC.