Keeping Otocinclus in the Aquarium – Here’s How it Works

Otocinclus Ear Grid Loricariid Catfish are beautiful small aquarium fish, which even make themselves useful by eating algae in the aquarium. They keep both the glass and the decoration clean and are a real eye-catcher. The peaceful Ear Grids Loricariid Catfish are fairly undemanding aquarium inhabitants, which are suitable for community, species or shrimp aquariums. Otos enjoy great popularity not only with experienced aquarists, but also with beginners.

Nevertheless, there are some things to consider when keeping the Octocinclus in the aquarium to ensure the best possible quality of life for the animals. All important information regarding the right tank, food, socialisation, water quality and breeding can be found in the following Aquarium Guide article.

Everything important about the Otocinclus in a nutshell:

      • South America is the home of the Octocinclus
      • The Otocinclus is considered by aquarists to be easy to keep and as an ornamental fish is well suited for beginners with basic knowledge
      • Ear grids Loricariid catfish should be kept in a group of at least 8 to 12 animals
      • The Otocinclus females are slightly larger and fuller than the males; in general, these fish reach an average size of five centimetres
      • The socialization with shrimps is possible
      • The Otocinclus needs soft water low in nitrates. The water temperature should be between 21 and 25 degrees Celsius, the carbonate hardness between 3 and 16° dKH and the total hardness between 4 and 10° dGH. The pH value may have values between 5.5 and 7.5
      • The pool for Otocinclus should be well structured and equipped with plenty of hiding places
      • The in South American ornamental fish has a dark back with very dark lateral stripes and a light belly
      • The Otocinclus reacts sensitively to freshly set up aquariums, as well as to the conversion of

Where do Otocinclus occur?

The four to five centimetre large Otocinclus is native to white and black water rivers in the north of South America and Central America. You can find the Otocinclus in the Amazon, Tocantins, Paraná and the Orinoco in Brazil. This freshwater fish is also at home in the bordering regions of Paraguay, where it can be found in slow-flowing, partly standing bank regions.

The native waters are also characterised by a lush root landscape, which Otocinclus likes to use as hiding places.

How many Otocinclus keep in the aquarium?

The peaceful Otocinclus is a schooling fish, which should be kept in a group of 8-12 animals. The peaceful animals get along very well with their conspecifics.

The group size is very important for the social behaviour of the animals. If the group is too small, this is noticeable by particularly shy animals that hide under the roots at the slightest movement. In such a case, the group should be increased again until the minimum of 8 animals has been reached.

In general, as with almost all other group fish, the more animals, the better. This applies in particular to the social behaviour of the animals.

For the welfare of the animals, the size of the tank must of course be taken into account. Due to its small body size, the Otocinclus can be kept from a tank size of 112 l – in a standard aquarium this corresponds to an edge length of 80 centimetres. The larger the aquarium, the more swimming-joyful animals can be held, which contributes substantially to the well-being of the ear grids loricariid catfish

How many Otocinclus you can keep in your aquarium is shown in the following table:

Basin sizeOtocinclus
112-120 litres8 animals
240 litres10-12 animals
350 litres12-15 animals

How to keep Otocinclus in the aquarium?

Ear grids Loricariid catfish require a very fine substrate. Fill your aquarium either with sand or very fine gravel and stock your tank with sufficient plants. The herbivore likes to nibble on fine-feathered plants, which is why broad-leaved aquatic plants are particularly suitable as a refuge for the animals.

It is essential that hiding places in the form of roots or stones should be available in the aquarium. Roots play a particularly important role: they are also found in large numbers in the animals’ native waters, which is why they should not be missing in the aquarium. In combination with dense border planting, which allows the largest possible swimming area at the bottom of the tank, the optimal tank structure is given.

The South American Otocinclus live in black water rivers in their homeland. As the name suggests, they are characterized by a low brightness. With dimmable LEDs and some dark roots, as well as foliage, the same effect can be achieved in the domestic aquarium, which contributes to the well-being of the animals.

As well as other catfish types, also ear-grids loricariid catfish are so-called intestine-breathers. This means that they swim to the surface of the water slowly or as fast as an arrow to absorb atmospheric oxygen, even if the water quality is excellent. This behaviour is completely normal for catfish and does not indicate poor water quality or even disease!

Which water values does an Otocinclus prefer?

You should try to imitate the natural habitat of the ear grids as much as possible. Consequently, it is essential to adjust the water values accordingly.

In freshly furnished basins ear grids loricariid catfish do not feel well at all. They need a very well run-in aquarium with algae coverings, which are just waiting to be grazed by them.

The animals feel particularly well with the following water values:

      • Temperature in degrees Celsius: 21 to 25
      • GH: 2 to 18
      • KH: 3 to 16
      • pH: 5,5 to 7,5

The water values should definitely be checked regularly. Make sure that the pH value is between 5.5 and 7.5. The carbonate hardness should be 3 to 16° dKH.

The Octocinclus feels especially comfortable at a water temperature between 21 and 25 degrees Celsius.

The nitrate content is also important: it must be checked regularly, as the animals are extremely sensitive to an increased No3 content.

If you look beyond this, the preferred water parameters of the animals are often easy to achieve even with conventional German tap water. Furthermore, the values are in ranges that can be combined very well with other species.

In combination with the peaceful behaviour of the Octocinclus, this leads to the fact that the animals can be socialised with an almost infinite number of species – but more about this in the next section.

Society of Otocinclus in the aquarium

The particularly peace-loving freshwater fish can be socialized with many other species without any problems. Even the socialization with shrimps, which often react very sensitively to other tank mates, is no problem at all with ear grids.

If socialization with other ornamental fish is planned, South American freshwater fish in particular have proven to be successful. The animals have very similar requirements regarding water quality, temperature and tank equipment. Especially South American characins, such as the red neon or the Ember tetra, should be mentioned here.

But also Endler Guppies, South American dwarf cichlids, like the Ram Cichlids or the Cockatoo Dwarf Cichlids are extremely well suited for socialization with Ear Grid Loricariidae.

Besides South American species, south-east Asian species such as wedge-tailed bearblings or honey gouramis can also be colonized by the peaceful Otocinclus.

The socialization with aggressive fish species is not recommended, also too large species should be avoided, otherwise the small five centimeters can quickly end up as food.

What does an Otocinclus eat?

The Otocinclus is a herbivore. It mainly rasp off algae coatings. This has a positive effect on the glass pane and on the decoration of your aquarium, as the Otocinclus is passionate about removing algae deposits.

Ear grids Loricariid catfish always need a proportion of fibres. Therefore it is necessary to equip your aquarium with real wood or roots. The small fish rasp off the wood. Moorland roots, naturally made of real wood, are particularly useful, and fallen leaves are also an important source of fibre. The latter are in turn present in the native waters of the animals, the black water streams.

Feeding with green food tablets is especially recommended if your aquarium is free of algae or if the algae coating is not very pronounced. The green food tablets provide Octocinclus with a balanced diet, they ensure healthy growth, a strong immune system and a high-contrast colouring.

You can also achieve a change in your diet with boiled or dried green fodder. Dandelion, nettle and spinach are ideal for this.

You can recognize the good health of your Octocinclus by the fact that it has a visible pea-sized brook. The little belly should be round. If the belly is straight or even collapsed, your otocinclus is undernourished and action is needed.

By the way, we show you a lot of information about the different types of aquarium fish food in our big guidebook article.

How are ear grids loricariid catfish bred?

Breeding the Otocinclus proves to be rather difficult in the aquarium, but it is certainly possible. We could already breed the animals in the community aquarium by lowering the temperature of the water first. While the lowered temperature (20-22°) lasted for a good week, the animals were fed with plenty of live or frozen food during this period. Then the temperature was raised and mating took place.

Ear-grids Loricariid catfish lay their eggs either on the aquarium glass or on the plants. After about three days the young animals hatch. They eat algae coatings and biofilms from the very beginning. You can additionally feed the just hatched fish with dust food.

The breeding succeeds above all in breeding tanks. In community aquariums, the young animals are usually eaten by their parents or the other aquarium inhabitants, which minimizes the survival chances of the animals extremely.

Conclusion: Ear grids loricariid catfish are peaceful & useful aquarium inhabitants

The peace-loving Octocinclus is a beautiful South American ornamental fish, which is very well suited for socializing with other species. This beginner animal is undemanding and if you adjust the water values to the original home you can enjoy these animals for several years.

The water temperature should be between 21 and 25 degrees Celsius, the GH value should be 2 to 18 and the KH value should be in the range of three to 16. In addition, the pH value should definitely be between 5.5 and 7.5 and the nitrate content of the water should be tested regularly to prevent the animals from dying.

Otocinclus feel especially comfortable when the lighting is not too bright and when there are enough aquatic plants and green algae in the pool to eat and hide. In order to be able to perceive the social behaviour of the animals in a particularly pronounced way and for their well-being, the animals should definitely be kept in groups of 8 animals or more – the more, the better.

Equip the aquarium with roots and real wood so that the Otocinclus can absorb the necessary fibres and hide.

Ear grids Loricariid catfish live on average five years, so if you take good care of the animals, you will be able to enjoy them for a long time.

Do you already keep Otocinclus in your aquarium and are you happy with the catfish? Show us your pictures.  

Keeping Otocinclus in the Aquarium – Here’s How it Works

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