The Best 40 Liter Aquariums

  • Guide to setting up a 40-liter aquarium
  • Buy a complete 40 liter aquarium kit
  • Aquarium planted in 40 liters
  • Plants for a 40 liter aquarium
  • P eces for a 40 liter aquarium

A 40-liter aquarium, without being an excessively large aquarium, allows us to have a good variety of fish, have a planted aquarium or make elaborate decorations.

I would say without a doubt that a 40-liter aquarium is perfect for a first contact with the aquarium hobbyist, without disregarding other smaller aquariums, which can be equally valid but sometimes become more complicated to handle.

40 liter aquarium kit


The best option, especially when our knowledge is basic, is to buy an aquarium kit in which all the elements are already configured.

We will not have to worry about choosing a filter, lighting or ballot box … since everything is a perfectly planned «set».

The best value for money to buy a 40 liter aquarium


The Marina LED 10G Kit is not exactly 40 liters as this manufacturer uses gallons and 10 gallons is 38 liters.
I would add a heater to this aquarium , essential if we want to keep tropical fish.

40 liter custom aquarium

One option that we always have available is to set up our own custom aquarium.

Although we are going to complicate a little more, the great advantage is that we will decide what elements are going to make up the aquarium: what filter to put, what lighting, heater … everything, to have the aquarium that we like the most.

Aquarium urn

The aquarium urn must be of good quality and made of glass. Although you can buy some in plastic, the clarity of the glass is irreplaceable.

We will find almost all kinds of urns on the market for a 40-liter aquarium, although the most common will be rectangular, with curved or straight glass.

The curved glass ones are beautiful and have the advantage of being in one piece, thus avoiding leakage problems. The problem is the price, they are somewhat more expensive.

Filter for 40 liter aquarium

For a 40-liter aquarium we can put any type of filter, both internal, external or backpack.
Personally I prefer backpack filters , which are installed on the side of the aquarium. I love external ones, but it is necessary to find a place to hide them and it is not always easy.

The important thing about a filter is its flow rate, in addition to the options of filter materials that it can mount.

I opted for these filters, which are capable of moving at least 120 liters / hour, the minimum for a 40-liter aquarium, in addition to giving the option of mechanical, biological and chemical filtration.

Its flow rate is adjustable , which allows us to lower or increase the intensity of the filtering, depending on whether the aquarium is very dirty or not, in addition to the fish’s own needs.


Heaters are not usually included in Aquarium Kits, at least not in most … although they are essential if we intend to take care of tropical fish .

The aquarium heater must be provided, we must not buy an excessively large one, but neither one that is not capable of heating the water.

Among the heaters available, the one I like the most is:

The quality of Sera products is indisputable, one of the best manufacturers of accessories and products for aquariums.

An aquarium planted 40 liters

One of the options that many beginners wonder is, if you can have an aquarium planted in 40 liters , and the answer is yes, you can.

It is necessary to use a nutritious substrate so that the plants can root, grow and obtain the food they need.

The ideal is to look for plants with low maintenance, if you want, that it is not necessary to add CO2, nor liquid fertilizers.

Plants for a 40-liter planted aquarium

  • Glosso . Upholstery plant with low CO2 requirements, but that needs good lighting, at least 30 lumens per liter.
  • Anubia Nana . Slow and compact growth, ideal for small aquariums. It can be located on the sides of the aquarium.
  • Amazon sword . For the back of the aquarium, due to its size.

All these plants grow in conditions of pH between 5.5 and 7.5, some can tolerate a somewhat more acidic pH.

Fish for a 40 liter aquarium

Once the plants have been chosen, we must choose which fish will accompany them.

With these parameters we must choose species of continental fish that support pHs between 6.5º and 8.5º.

  • Betta Betta fish need a pH between 6 and 8. As a rule, you only have to put one male in, he is very aggressive, in an aquarium of this size there should only be one specimen.
  • Zebra fish. pH between 6 and 8, it reaches about 5 centimeters as an adult. It can be combined with other fish.
  • Neon tetra. Withstands wide variations in pH, between 4 and 7.5. It is perfect for a small aquarium, they measure only 4 centimeters.
  • Corydoras panda. They occupy the bottom of the aquarium, so that they do not compete for space with other fish. They measure about 5 centimeters, and are perfect with a pH between 6 and 7.4.

How many fish can I put in a 40 liter aquarium?

Not many…

The combinations of fish you make must take into account several aspects, such as the size that the fish will have when they reach adulthood, as well as the space available once we put plants and decoration.

A possible combination, for example: a small school of 6 Neon Tetra, with 3 panda Corydoras.

You can modify the number of fish, taking into account their social needs (you cannot put a single neon tetra), water quality, compatibility (they are sociable or not) and available space.

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