How many fish can be kept in an aquarium – how to calculate the number

Determining how many fish can live comfortably in your tank is one of the most crucial choices you’ll make during the exciting process of setting up an aquarium. To avoid stress, disease, and even death in your fish, it’s important to find the ideal balance.

There are other factors besides tank capacity to take into account. What is the maximum number of fish that can live in harmony depends on a number of factors, including species, size, and behavior. While some fish may favor hiding places or places with less competition, others may require more room to swim.

Having the proper balance means that your aquatic pets will live in a healthy environment. We’ll walk you through the process of figuring out how many fish is the right amount for your aquarium in this post, so you can create a vibrant underwater world.

What is the threat of overpopulation

The fish will start to suffer from a lack of oxygen if the jar is overcrowded, which will be detrimental to their health. There will also be a battle for living quarters, which is dangerous for the fins.

Ammonia, nitrates, and nitrites rise in the water as a result of large fish releasing large amounts of waste into it. This can lead to the death of pets.

Of course, you can add a strong external filter, change the water more frequently, and add a lot of plants to an aquarium that is overcrowded. The fish won’t become poisoned and perish in this scenario. Will they be cozy, though? Naturally, no. Furthermore, a fish-heavy aquarium is unlikely to appeal to you.

Calculating the number of fish in an aquarium

There are several counting techniques, including both contemporary and traditional approaches. We will walk you through each method—including the flawed ones—and point out all of its drawbacks.

Technique 1

Most often, novice aquarists are offered to calculate the number of fish based on their length. In this case, there is 1-2 liters of water per 1 cm of pets. This calculation is outdated and not very correct. I will explain why. Following this calculation, 10 goldfish of about 10 cm in size can be populated in a 100 l aquarium. Goldfish release a lot of waste into the water, which will be difficult to handle even for a powerful external filter. Over time, the owner of such a jar will face the death and illness of pets. And imagine 4 adult 25 cm astronotus in a 100 l container. There will be no room for them to turn around. That is, this formula does not work correctly.

Technique 2

The theory that states that one fish should be given five liters of water is equally well-liked. However, it fails to consider the fish’s size once more. Only medium-sized, non-aggressive fish, like barbs, or even smaller ones, can use it.

Technique 3

The rule "3.5 cm per 5 liters of water" should be used to determine the number of pets, as this would be more accurate. In this instance, the length of every aquarium inhabitant is 3.5 cm. Applying this guideline, take into account:

• Maximum size of adults.
• The shape of the pets you are buying. Fat fish produce more waste than slender and elongated ones (for example, gourami and molly, pecilia and danio). This means that the volume per full fish should be greater than per elongated one.
• The actual volume of water in the aquarium will be approximately 15% less than empty. These 15% will be taken up by the soil, underfilling to the top, plants and other decorative elements.

Technique 4

Let’s now consider figuring out how many fish there are based on the water’s surface area. The length and width of the container are multiplied to determine the area. More fish can be put in the jar and the water will have more oxygen in it the larger the area. A comfortable ratio is thought to be 90 cm² of surface area for every 3 cm of length in slender fish and 150 cm² of surface area for large, full species of fish. It’s crucial to leave a tiny buffer when figuring out how many pets to have using this method.

• Full: for every 3 cm – 150 cm².
• Slender: for every 3 cm – 90 cm².

Example of calculation: aquarium with dimensions of 45 cm by 100 cm. The area is 4500 cm^�, or 100 x 45. We intend to raise 6-centimeter full fish, which equates to 300 cm² per fish (150 cm² for every 3 cm of length). We obtain 15 fish (4500 / 300). Consequently, for slender and elongated 6-centimeter fish, 4500 / 180 = 25 pieces. Remember to leave a little reserve, like 10%.

It’s important to take into account the size of the tank, the species of fish, and their growth potential when figuring out how many fish can be kept in an aquarium. One inch of fish per gallon of water is a general rule of thumb, however this varies based on the needs of the fish for oxygen, space, and territorial behavior. It’s critical to plan ahead and conduct research to establish a healthy, balanced habitat for your fish because overcrowding can result in stress, poor water quality, and health problems.

Number of liters for certain fish

A few fish keepers talked about their experiences with maintaining fish in aquariums and specified the number of liters required for each type of fish water. The following guidance is only intended for jars with filters and routine maintenance.

• Small aquarium fish up to 4 cm in size (guppies, neons, rasboras) are kept in containers from 20 l. At the same time, there should be at least 1 liter of water per individual, but more is better.
• For fish up to 6 cm long (pecilia, minors, ternetia), the minimum stocking density is 2 liters per 1 individual.
• For peaceful aquarium fish up to 10 cm long (swordtails, barbs, mollies, apistograms), you will need an aquarium with a volume of 50 liters. Stocking density from 10 to 15 liters per 1 individual.
• Labyrinth fish are placed in an aquarium depending on their size. For example, one cockerel will be comfortable in a 20 liter aquarium. For a pair of marble and gold gouramis, there should be 30 liters. The number of honey and chocolate gouramis is calculated based on the rule of 10-15 liters per pair.
• For a comfortable habitat, discus need an aquarium of 200 liters. Only 2 fish will get along in such a capacity.
• For one goldfish, ancistrus and angelfish, there should be 50 liters of water. Only in a spacious aquarium will they feel comfortable comfortable.
• Large catfish measuring 30-40 cm are kept in spacious jars with a capacity of 200 l.
• For large fish, such as arowana, snakehead, flower horn, Indian knife, you will need a container with a volume of 500 liters.

It’s crucial to take into account the size of your tank as well as the unique requirements of each species when figuring out how many fish you can keep in your aquarium. When starting out, it’s always preferable to start with fewer fish and progressively increase their numbers as you gain experience. This is because overcrowding can result in stress, disease, and poor water quality.

To maintain a healthy fish population, filtration, regular maintenance, and water quality are essential. Adding too many fish at once can overwhelm the system and lead to issues, even if your aquarium appears large. You can make necessary adjustments by keeping an eye on your fish’s behavior and overall health.

Ultimately, there’s more to creating a healthy environment for your fish than just following a recipe. A happy and healthy ecosystem will be ensured if you are aware of the particular needs of your aquarium’s fish inhabitants. Build and maintain your underwater world with enjoyment, taking your time and doing your homework.

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