Nano aquariums have been enjoying growing popularity among aquarium fans for some time now. But what is a nano aquarium anyway? We have put together everything worth knowing for you here and give you tips for stocking and planting your underwater world.

What is a nano aquarium?

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A nano aquarium is, as the name suggests, an aquarium that is significantly smaller than normal commercial aquariums. The capacity can be quite different. There are nano aquariums with a volume of about 60 litres, but there are also significantly smaller ones. Cube-shaped aquariums, so-called Nano Cubes, are also sold in sizes of 30 x 30 cm (30 litres) and 25 x 25 cm (20 litres). The specific size of your aquarium will of course determine which animals you can keep in your nano aquarium. Because not all species are suitable for living in such a limited space.

First of all: We would strongly advise against keeping fish in an aquarium that holds less than 30 litres. In 1998, the Federal Ministry of Food, Agriculture and Consumer Protection even published minimum requirements according to which an aquarium may not actually have a capacity of less than 54 litres when keeping ornamental fish. In order to keep classic aquarium fish such as guppies, the nano aquaria are actually much too small. But there are also species that you can keep without any problems in a tank with a capacity of 30 litres or more. And of course it is also possible to set up a nano aquarium completely without animals, but that is another matter. We will limit ourselves here to setting up a freshwater nano aquarium.

Advantages and disadvantages of mini tanks

First things first: establishing a biological balance in a nano aquarium is much more difficult than in a large tank. This is simply because a larger body of water is more forgiving of mistakes. With a nano aquarium, the rule is: small mistakes, big consequences. Nano aquariums are more prone to overfeeding or even minimal fluctuations in water quality and temperature.

Aquarium beginners are often tempted to buy a nano aquarium because they think it is easier to maintain than a large one. But far from it – especially because of the small size it is much more difficult to establish a biological balance in the aquarium. Special care should be taken in case of possible overfeeding – the decomposing food residues deteriorate the water quality, and this can lead to your animals dying. We recommend that you check the water values twice a day and make a weekly partial water change. The best way to change the water is explained in the article Water change aquarium – harmful or not for you.

Another disadvantage of the Nano-Aquarium is: The aquarium may be nano – the costs are not. The equipment of nano aquariums hardly differs from that of conventional aquariums; many utensils are the same only in a smaller form. Also in the purchase price does not differ noticeably from that of a normal aquarium. The prices for a nano aquarium range between 90 and 200 Euros. The maintenance costs, however, are lower than those of a classic aquarium. Due to its limited size, you need less electricity and possibly not even a heater. Complete sets are available on the market, in which the aquarium and the accessories are perfectly matched. In any case, we would like to recommend you to buy such a set for the beginning.

Of course, nano aquariums also offer numerous other advantages: They are easy to transport and can be placed in any apartment. And last but not least they look beautiful and are well suited for observing small creatures such as dwarf crabs or dwarf shrimps.

Filling for a nano aquarium

In principle you can set up a small aquarium just like a large one. However, you should bear in mind that space in a nano aquarium is limited, so choose your plants and aquarium inhabitants accordingly. The best thing is to make a precise plan before you start setting up your nano aquarium and don’t forget to get good advice from a professional. In the following we will introduce you to possible nano-dwellers.

Fish for the Mini-Aquarium

If you decide to stock your nano aquarium with fish, you must be careful not to overstock the aquarium. Not all fish species are suitable for small aquariums. Due to the cramped conditions in the Nano-Aquarium, the selection of the fish should be very carefully considered – they should not grow larger than 4 cm at the adult age. As a rule of thumb for the stocking is: for every litre of water there is one centimetre of fish. So you can stock a 30-cube with five to ten fish and a 60-cube with ten to twenty fish.

In any case, limit yourself to one or two species and get several fish from each species so that they don’t feel lonely. If in doubt, take a few fish less than too many and pay attention to their habits and needs: Quiet fish don’t like to live with swimming fish and vice versa. In addition, the fish should find a habitat in the aquarium that corresponds to their natural behaviour. For example, shy fish need shelter and schooling fish need space to swim. Also pay attention to their eating habits and whether they prefer soft or hard water – all these factors play a role.

In the following we will introduce you to two fish species that are suitable for nano aquariums.

Mosquito Bearling (Bororas Brigittae)

Mosquitoes are very pretty and can enhance your Nano-Aquarium optically noticeably. They have a bright orange-red colour with black markings on the sides of their body. The small fish originally come from the tropical rainforests of Sumatra, Sulawesi and South Borneo and rarely grow over 2 cm in size. Their bright colour is best seen when the aquarium is well planted. They do not make great demands on the water quality, but feel most comfortable in slightly acidic and soft water. The ideal water temperature is 23 to 28°C. In nature they like to feed on worms, crustaceans and plankton, but in the aquarium they like to eat granulated or dry food with a bit of habituation.

Mosquitoes have a rather jumpy disposition, which is why it is recommended to socialize with calm fish.

Guinea fowl danio (Danio margaritatus)

The guinea fowl bear is native to Burma and Thailand and only grows to about 2 cm. Because of its bright colours and its peaceful nature, it quickly became a favourite of aquarists. It has a blue ground colour, its belly is white to orange and it has golden yellow dots on the sides of its body.

The guinea fowl is a bit jumpy and shy, but very uncomplicated in keeping. Therefore it is very well suited for keeping in a nano aquarium. Since the guinea fowl is a fish that needs retreat possibilities, a dense planting of the aquarium is recommended. It is also a shoal fish and should not be kept in groups of less than five specimens. The ideal water temperature is 18 to 22°C.

Guinea fowl like to eat live, frozen and dry food, but you should be careful never to put more food into the aquarium than can be eaten immediately to avoid overfeeding.

Shrimps in a nano aquarium

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Dwarf shrimps are excellent for stocking your nano aquarium. They are comparatively undemanding, peaceful and take up very little space. As excellent cleaners, they also keep the algae growth in check. They are cultivated in many different colours and can significantly beautify your underwater world.

From a volume of twenty litres we can recommend a starting stock of ten to twenty animals. Adult shrimps do not grow larger than 3 cm and do not make any special demands on the pool’s equipment. However, it is important that your nano aquarium has a filter. It cleans the water and ensures that the water is enriched with oxygen through the constant movement of the water surface.

Dwarf shrimps are good algae killers and omnivores with a preference for vegetable food. A varied diet is nevertheless important. For example with special shrimp and/or fish food, but they also like crushed peas and spinach.

Shrimp are also easy to care for when socialising. They are very sociable and behave peacefully towards other aquarium inhabitants. Therefore they can be socialized with fish, snails and also peaceful crabs without hesitation.

Shrimp are tolerant of water levels, but nevertheless keep a close eye on the water parameters and check them daily. Find out which shrimp are suitable for your plans, especially if you are a beginner. Below we present three types of shrimp.

Red dwarf shrimp

The red dwarf shrimp is one of the best known dwarf shrimp because of its beautiful red colouring. It is easy to care for and well suited for beginners. The shrimp, which originates from South-East Asia, grows up to 2.5 cm long and behaves absolutely peacefully towards its fellow inhabitants; that is why it can be socialised with all of them. Its favourite water temperature is 22 to 28°C.

It is also easy to reproduce – you can count on about 25 baby shrimp per month. But you will have to transfer them to other tanks soon to avoid endangering the delicate biological balance in your nano aquarium.

Tangerine shrimp

The mandarin shrimp comes from Sulawesi in Indonesia. It is bright orange in colour and grows up to three centimetres in size. Although it is difficult to breed under aquarium conditions, it is nevertheless well suited for aquarium beginners. From 20 litres capacity on you can keep a group of ten individuals.

The mandarin shrimp is peaceful and frugal and can be easily socialized with other shrimp or ornamental fish. As food it loves algae and dried leaves, but is also not averse to commercially available dry and granulated food for shrimp and/or ornamental fish.

Red-tailed shrimp

The red-tailed shrimp comes from Taiwan and is not as colourful as the other two species, but still very suitable for beginners. Its name is derived from its red colored tail area. The rest of the body is bright and transparent and shows different patterns, for example many small dots. Red-tailed shrimp like dense planting and like to eat algae. They grow to about 2.5 cm in size, are peaceful and are easy to socialize. Basically you can keep redtail shrimp together with all other dwarf shrimp species. However, you should then be aware that the beautiful colours of the other shrimp species can be lost through unwanted cross-breeding – at some point the offspring become grey-brown and unspectacular. To avoid this, you can consult crossbreeding tables that you can find on the internet.

Red-tailed shrimps are very easy to breed because the females do not give birth to larvae, but give birth to 20 – 40 fully developed, almost transparent young once a month. As with the red dwarf shrimp, you should then soon transfer the shrimp offspring to other tanks.

Crabs in a mini aquarium

Most crabs grow quite large. If you want to stock your nano aquarium, you should stick to dwarf crayfish (for example of the genus Cambarellus), because they don’t grow bigger than three to five centimetres. They can also be kept in mini aquariums with a capacity of ten litres or more. The reason for this is that dwarf crayfish hardly ever swim – for them, the size of the base area is more important than the height of the tank. Out of love for animals we still recommend you to choose a slightly larger tank.

Dwarf crayfish are also animals that are tolerant of water values. They also have no interest in destroying plants, which means that you can create your underwater world as you like. It is important that you offer the crabs enough hiding places, such as roots. They also like to dig a shelter in sand or gravel. It is also important that you make the nano aquarium escape-proof, because crabs can climb very well.

There are more peaceful and more aggressive species. If you want to socialise dwarf crayfish with dwarf shrimp, make sure that you get crayfish that do not consider the shrimp as food. Crayfish and shrimp normally live in different habitats, so socialising needs to be well planned. Dwarf crayfish can be socialised very well with Bearblings, however – and snails are eaten.

The dwarf crayfish (Cambarellus)

Dwarf crayfish are quite easy to keep. Therefore they are well suited for aquaristic beginners. In nature they like to live in standing to slowly flowing river sections in East Asia and North America. Due to their small size you can also equip your nano aquarium with them.

The food should be as varied as possible. Basic food is available in the shops, but the crayfish also like boiled peppers, peas or Brussels sprouts. They also have no problem with food that is actually designed for fish. But most important is foliage. Autumn leaves should never be missing as a food supplement in a dwarf crayfish tank. Dwarf shrimps also take part in the decomposition process of leaves, but the actual destroyers are the dwarf crayfish. You can collect the foliage yourself in autumn or otherwise order it on the Internet. Most European deciduous trees are very suitable for this, especially oak and beech, but the leaves of the hazel bush are also very popular.

Again, you must be careful never to put too much food in the aquarium. What has not been eaten after one hour has to go out.

Snails – busy caretakers in the aquarium

Snails can be pests, but they can also be fosterlings. For this reason and because they are undemanding, they are well suited for stocking your nano aquarium. Make sure to always keep at least three animals together. To keep the algae in the aquarium in check, snails are a very good choice, because they love to eat them.

Zebra snail

The zebra racing snail grows to a size of two to three centimetres and has a pretty shell pattern from which its name is derived – it is yellow with black stripes. It is particularly interesting for the stocking of your nano aquarium because it feeds primarily on food remains and algae, but not on plants. It is therefore really useful and can help you to maintain a healthy biological balance in your nano aquarium. It is also recommended for socializing with shrimp, because it is peaceful and gets along well with shrimp. If they only have access to fresh water, the zebra snails cannot reproduce in the aquarium, so you don’t need to be afraid of a snail plague.

Antler snail

The antler snail is also recommended for keeping in a nano aquarium, because it cleans. It diligently cleans furnishings and windows and also tirelessly destroys algae. Of course, a sufficient supply of algae must be available for this. Therefore you should only put antlers snails in the aquarium after it has been set up for a while.

The antlers of the snail, from which its name is derived, are not feelers, but are in the form of tips on the shell. Antler snails appear in many pretty colour drawings. They also have a peaceful disposition and can therefore be kept together with shrimps. Furthermore they cannot reproduce in fresh water.

Plants in a nano aquarium

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Planting plays a major role in the nano aquarium. It not only looks beautiful, but also provides protection and care for the animals. In principle, the plants create a habitat that is similar to that of the animals in nature. This ensures that the animals feel comfortable and also improves the water quality.

A small aquarium naturally requires small plants. There are also special nano-plants which are particularly suitable for the nano aquarium. There are starter kits on the market, which include the plants. We present you here the moss balls, because they are not only small but also pretty.

Moss balls

Contrary to what the name suggests, moss balls do not consist of moss, but of threads of algae. However, they have a moss-like structure and some other properties that moss also has. They look like fluffy little balls of fabric. They are particularly suitable for beginners because they do not grow uncontrollably and generally do not make high demands.

You can place the moss balls flexibly. So you don’t have to tie them down, just place them anywhere in the aquarium where they will soak up water. In fact, you should let the moss balls roll over the substrate more often so that they keep their beautiful spherical shape. Of course you have to choose small moss balls. They reach a maximum diameter of ten centimetres – for the nano aquarium a diameter of three centimetres is recommended.

Moss balls can be combined particularly well with a shrimp stocking. Microorganisms that use the shrimp as a food source settle on the plants. If the animals feel comfortable, the offspring will also not be long in coming.


The attraction of nano aquariums is that they allow beautiful underwater worlds to develop in a very small space. Even though the conditions for this may be somewhat more difficult than in classic aquariums, it is certainly feasible. It is important that you do not overstock your aquarium and check the water values regularly. If you take good care of your nano aquarium, you will enjoy it for a long time.

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