How many fish can I put in an aquarium?

One of the questions I usually get is how many fish can I put in an aquarium?

When we buy our first aquarium , we are clear about a number of fish that we want to have, depending on the size of the aquarium.

Fortunately, there are so many species of fish that we can acquire and care for, with such a high variety of shapes and colors, that we would like to have them all.

It’s like entering a free Buffett, you know you can’t eat it all, but you would love to.

As can happen to you in the free Buffett, putting in many more fish than can live in good conditions, will have a disastrous result.

Is there a way to know how many fish I can put in an aquarium?

Yes. There are some rules, let’s say «basic» , although at all times we must use common sense, it is better to sin by default and that the fish have a lot of space , than to sin by default and are crowded together, which will cause stress and disease situations.

One liter of aquarium water, for every centimeter of fish

There is a fairly widespread rule in aquariums, to establish the appropriate number of fish that we can introduce into an aquarium.
This rule states that we must reserve one liter of water, for every centimeter that a fish has. Thus, a fish measuring 10 centimeters would need 10 liters of water.
The problem we have when we generalize is that we are not taking into account the thousands of possible variables.
For small tropical fish , such as tetras, bettas or platies, reserving a liter or better two liters of water per centimeter of fish, is a good measure.
However, we have bigger fish or fish that make more dirt, they will see that space very limited.

Determine how much space each fish needs

One liter of water per centimeter of fish, when we talk about African cichlids , more so if they are American and we have a well-planted aquarium, or when we talk about fish such as koi carp and goldfish , which usually get very dirty … little space is made. There are aquarists who recommend 10 liters of water per centimeter of fish, for these varieties of fish that grow a lot or that make a lot of dirt. But we are forgetting another detail, such as the aggressiveness or territoriality of the fish. Those dominant species that like to determine their space within the aquarium will need a larger aquarium.

Summarizing a little, we will have to take into account the following conditions, to determine how many fish we can have in the aquarium:

• Amount of waste produced by each variety of fish. Larger varieties tend to generate more waste and will need more space.
• Size that they will have as an adult. A rookie mistake is not contemplating how tall our pets will be when they reach adulthood; a young guppy is 1 centimeter when we buy it, an adult specimen is 5 centimeters.
• Poecylids are one of the most widely sold freshwater aquarium fish, one of the reasons is that they are very easy to reproduce … and there may be another error, if we do not take into account that the population of our aquarium «can grow» .
  Be careful with the number of males and females that we introduce.
• When calculating the number of fish that can fit, using the typical rule of the liter per centimeter of fish, it must also be noted that the aquarium is not only fish and water: there are plants, decoration , filters … the useful volume at the end will be less .

Aquariums by size

• Small aquariums
• 10 liter aquariums
• 20 liter aquariums
• 30 liter aquariums
• 40 liter aquariums
• 50 liter aquariums
• 60 liter aquariums
• 80 liter aquariums
• 100 liter aquariums

Aquarium type

• Complete aquarium kits
• Nano aquariums
• Prawns
• Aquariums for Bettas
• Tortugueros
• Aquariums for kids
• Farrowing
• Cheap aquariums

Trademarks

• AquaLed
• Tetra

Oxygen exchange in the aquarium. Calculation of the area

So far we have been commenting on the “physical” space that the fish needs to live, but we have not talked about another of its needs: oxygen.
I don’t know if you know, but if I don’t tell you, gases are exchanged on the aquarium surface, so that the aquarium releases carbon dioxide (CO2) and the oxygen present in the air and necessary for the life of the fish. , just dissolved in the water. There is a rule, which is to calculate the surface of the water to know how many fish our aquarium can have, based on this gas exchange. This rule says that an aquarium can hold one centimeter of fish, for every twelve square centimeters of surface area.

The Spanish society of aquarists has established guidelines to determine how many fish we can introduce into an aquarium, depending on its surface. The calculation would be as follows:

• Cold water fish : 62 square centimeters, for every centimeter of fish.
• Tropical fish: 26 square centimeters, for every centimeter of fish.

This rule also suffers from defects, such as not taking into account the total liters of the aquarium , so that the taller and narrower aquariums would be harmed in terms of the number of fish they can have.
As we are generalizing, the particularities of each fish are not taken into account: territoriality, aggressiveness or species.

Everything you need to maintain your aquarium

• Best digital pH meter
• Best Aquarium Test
• Best anti-algae
• Best bacteria for aquarium
• Best siphoner for aquarium
• Best Aquarium Water Clarifiers
• Best reverse osmosis filters for aquarium
• Best UV lamps for aquariums

Guide table: Calculate how many fish can I put in an aquarium

I have tried to make some tables, which serve as an orientation so that you can decide how many fish you can have in an aquarium.
How is a basic table, you must combine species and sizes, so that you can draw your own conclusions: