What Fish Can Go In A 15 Litre Tank? Best Fishes & Calculation

A capacious aquarium cannot always be installed at home, therefore small volume tanks, within 15 liters, are popular. Before settling in, it is important not only to create the necessary living conditions for the pets, to prepare the decor but also to determine what fish can go in a 15 litre tank and how many fish can be kept in a 15-liter aquarium.

what fish can go in a 15 litre tank

signs of aquarium overcrowding

Overcrowding negatively affects the life of fish. A large number of residents leads to a lack of oxygen, water saturation with ammonia, nitrates, and harmful nitrogenous compounds resulting from the decay of feces and food residues.

The imbalance of the habitat causes fading of the color of the fish, growth retardation, and problems with reproduction. Frequent water changes, the presence of an external filter, and plants prevent poisoning and death of pets.

But even in such conditions, they will be uncomfortable, because. with overcrowding, a struggle for living space begins, and infectious and bacterial epidemics arise.

signs of aquarium overcrowding:

  • the color of the fish becomes faded;
  • mature individuals decrease in size relative to physiological norms for a given breed, young animals slowly or do not gain weight at all;
  • pets gasp for air and are often near the surface of the water.

How much capacity does a 15 litre fish tank have?

A 15-liter aquarium does not take up much space, but you can create an original design in it and populate it with several pets.

At the same time, the allowable number of fish varies depending on the shape of the tank, the equipment installed, decorative elements and vegetation.

15 liter fish tank shapes

Common shapes of 15 litre Aquarium:

  1. Round. Harmoniously combined with any style of interior. They are convenient to move, but they do not have the necessary area for high-quality aeration, and also distort the light and image.
  2. Square. They do not have a bad effect on the inner world of pets, they are easy to clean from the inside.
  3. Rectangular. Differ in the correct review and comfort for inhabitants. The proportions are convenient for care activities. It is important that the width is equal to the height, and the length is 2 times the width.

EQUIPMENT For 15 liter fish tank

Despite the capacious volume, 15-liter tanks require the installation of separate devices:

15 liter fish tank decor AND VEGETATION

It is not recommended to overload the space with large-sized decorations or many small elements. It is important to use purified soil, without dyes. Plants should be planted to adjust the number of harmful nitrites, nitrates, and ammonia. For this, dwarf varieties of the Amazon, anubias, echinodorus, cryptocoryne are suitable.

Calculating how many fish in a 15 litre tank?

There are several calculation options, each of which has advantages and disadvantages.


Thus, 1-2 liters of a waterfall on 1 cm of body length.

At the same time, the characteristics of the breeds are not taken into account, a minimum space is created to ensure the physiological health of pets.


Another popular method, according to which 1 individual requires 5 liters of water. In this case, the size of the fish is not taken into account. The technique is suitable for non-aggressive average residents.


The number of fish is determined according to the rule: 3.5 cm per 5 liters of water, where 3.5 cm is the length of all inhabitants.


The allowable number of inhabitants is calculated taking into account the surface area of ​​the water. To determine it, the length of the aquarium must be multiplied by the width. The larger the area, the more oxygen, and individuals can be settled in the tank.

For large and full species, the ratio is considered optimal, in which for every 3 cm of body length there is 150 sq. cm of the surface, and for elongated and slender species – 90 sq. cm.

With this calculation, it is desirable to provide for a margin.

what fish can go in a 15 liter tank? (Best 10)

There are many types of fish can go in a 15 liter tank, so they can be settled in pairs or schools:

Catfish ancistrus Fish Can Go In A 15 Litre Tank

One of the most popular small species. The fish have different colors, are distinguished by diligence and the ability to clean the glass of the tank.

catfish ancistrus


Beautiful fish, characterized by a variety of shapes and colors. For small volume, you can choose 2 pairs.

guppy for 15 litre fish tank


They are original, have veil-like fins and bright colors. They differ in fighting character, so it is better to keep them separately from pets of other species.



Small bright fish that feel comfortable in flocks. For small aquariums, groups of 4-6 individuals are suitable.


This species is unpretentious to the temperature and composition of the water. Fish prefer to swim in the middle of the tank.

Copper tetra Fish Can Go In A 15 Litre Tank

This species is recommended to be kept in pairs. Adults reach a length of 4-6 cm, have a reddish color, non-aggressive.

Catfish corridor

The fish are predominantly nocturnal, but are active during the day, looking for food in the ground.

Cherry barb

Mobile pets that spend a lot of time in search of food. Unpretentious in nutrition, have a pink-cherry color.


It will serve as a decoration for the aquarium, but for a capacity of 15 liters, it should be chosen subject to a minimum of population, good filtration, and aeration.


You should choose those subspecies that are suitable for small aquariums, such as artificially bred goldfish.

15 liter tank CARE

Medium-sized aquariums are comfortable to use, but some nuances must be taken into account when arranging and maintaining them:

  1. Be sure to install a filter, preferably a pump with a sponge for cleaning.
  2. Equip the tank with an aerator to saturate the water with oxygen.
  3. Maintain the desired temperature of even a small container with a heater.
  4. Equip a backlight (a built-in lamp will do).
  5. Plant plants that will help establish the correct amount of nitrates, ammonia and serve as a natural hiding place for small pets. For a compact aquarium, ferns, anubias, cryptocoryne, cladophora, marsilia blix, Brazilian lileopsis are good.
  6. Periodically clean the decor elements and appliances from dirt and control the quality of their work.
  7. Be sure to change the fluid weekly with an update of 15-20% of the volume. Clean the container with a scraper. Remove dirt, plaque, food residues from surfaces as they become dirty.

15 liter tank PROS AND CONS

More often, small aquariums are chosen by beginner aquarists, believing that they are easier to maintain than large ones. But this option has both advantages and disadvantages.

15 liter tank Pros:

  • space saving;
  • low cost;
  • cheap service;
  • minimum decor;
  • mobility.

15 liter tank Cros:

  • cloudy water;
  • the discomfort of the inhabitants due to lack of oxygen;
  • difficulty in establishing biological balance;
  • frequent, sudden changes in water temperature;
  • fast evaporation;
  • difficulties in locating the necessary equipment;
  • limited choice of inhabitants.


The fish can go in a 15-litre tank and can be adopted for any small aquarium. We hope we have cleared all questions in your mind about 15 litre tank.

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