Zebra Oto (Otocinclus cocama)

Zebra Oto (Otocinclus cocama) is a small, peaceful suckermouth catfish from Peru, best known for its distinctive dark-and-light pattern and its habit of grazing soft algae and biofilm from aquarium surfaces. In the UK aquarium hobby it is also sometimes sold as the Zebra Otocinclus. It is an attractive choice for a mature planted aquarium, but it should not be treated as a disposable “clean-up fish”.

Use the size selector on this page for the current supplied size, price and availability. Plan the aquarium around the adult fish and the needs of a proper social group rather than the delivery size.

What you are buying

• Common name: Zebra Oto / Zebra Otocinclus
• Scientific name: Otocinclus cocama
• Family: Loricariidae
• Adult size: around 4–5 cm
• Temperament: peaceful and social
• Diet: biofilm and algae grazer that also needs supplementary food
• Best suited to: mature planted or peaceful community aquariums

A mature aquarium is essential

Zebra Otos do best in an established aquarium with visible biofilm, soft algal growth and plenty of mature surfaces to graze. A tank can be fully cycled yet still be too new or too sterile to provide enough natural food. Wood, smooth stone, broad-leaved plants and older aquarium surfaces are particularly useful.

For a group, a longer aquarium with a good footprint is more useful than a very small nano tank. Around 60 litres or more is a sensible starting point for a small group, with additional space preferred where the aquarium also contains other bottom-dwelling fish.

Water and filtration

A practical range for established stock is around 22–26°C, with soft to moderately hard water and a mildly acidic to near-neutral pH. Stability is more important than trying to hit one exact number. Ammonia and nitrite must remain at zero, and nitrate should be controlled with sensible stocking and regular water changes.

Provide good oxygenation and gentle-to-moderate flow. Zebra Otos appreciate clean water and surface movement, but they should still have calmer places where they can rest and graze without fighting a strong current. Cover filter intakes where necessary, especially with smaller fish.

Group size and behaviour

Otocinclus are social fish and are more confident when kept with their own kind. We recommend keeping at least six where aquarium size and food availability allow. A lone specimen may hide more and can be easier to overlook if it starts losing weight.

Healthy Zebra Otos spend much of the day moving between glass, plants, wood and stone. A gently rounded belly, clear eyes, open fins and regular grazing are useful signs of good condition.

Feeding

Natural algae and biofilm are important, but they are not a complete feeding plan. Offer a good-quality algae or spirulina wafer, specialist herbivore food, and small portions of suitable blanched vegetables such as courgette. Rotate foods rather than relying on one product.

Do not deliberately underfeed Zebra Otos to make them eat more algae. A spotless aquarium can leave them short of food, and slow weight loss is one of the most common husbandry problems with this group. Remove uneaten vegetables before they spoil the water.

Tank mates

Zebra Otos suit peaceful community aquariums with small tetras, rasboras, pencilfish, Corydoras and other calm species that will not harass them or dominate every feeding opportunity. They can also live with many ornamental shrimp and snails in a suitably mature aquarium.

Avoid large predatory fish, aggressive cichlids and very boisterous bottom feeders. The aim is to give the Otos uninterrupted access to grazing surfaces and supplementary foods.

Plants and aquascaping

This species is particularly well suited to planted aquariums. Anubias, Java fern, Cryptocoryne, wood and smooth stones all provide useful grazing surfaces. Moderate lighting can encourage a manageable layer of natural growth, while shaded areas help newly introduced fish settle.

A dark background and natural hardscape also make the Zebra Oto pattern easier to appreciate without changing the fish’s environment simply for display.

Acclimation and quarantine

Zebra Otos can be sensitive after transport, especially if they arrive lean or experience a sudden change in water chemistry. Match temperature carefully and acclimate gradually to the prepared aquarium. A separate, mature quarantine tank is strongly recommended before adding new fish to an established community.

During quarantine, check body condition and feeding response every day. If a fish is losing weight, test the water first and make sure it has access to suitable food before reaching for medication.

Before ordering

Choose Zebra Otos if you have a mature, stable aquarium with established grazing surfaces and enough room for a proper group. Reconsider if the tank is newly set up, has no visible biofilm, or if the only reason for buying the fish is to solve an algae problem.

Current supplied size, price and stock are shown by the live options on this page so the husbandry information can stay accurate even when commercial details change.