A small, peaceful, and highly popular algae-eating catfish native to South America. They are obligate shoaling fish that thrive in mature, heavily planted aquariums with steady water parameters and a constant supply of soft green algae and biofilm. They are extremely sensitive to uncycled or pristine/new tanks without natural food sources.
At a Glance
Tank Requirements
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Water Parameters
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Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard
The standard Otocinclus available in the trade. Must be kept in groups of at least 6 to feel secure. Ensure the tank is fully mature (running for several months) before adding them to guarantee sufficient biofilm and algae growth.
Same care requirements as the base species
Also known as: Wild Type Oto, Common Oto
Top Tank Mates
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🟢Ideal Tank MatesOtocinclus Care Guide Summary
The Otocinclus, scientifically known as Otocinclus vittatus, belongs to the Catfish family group. Adults reach a maximum size of approximately 4 cm and have a depressed body shape with a slow growth rate. Classified as peaceful, this species primarily occupies the mid-level and bottom zones of the aquarium and produces a low level of biological waste.
To thrive, the Otocinclus requires a freshwater only aquarium with a minimum volume of 38 litres and a tank length of at least 45 cm. Water temperature should be maintained between 21°C and 26°C, with a pH range of 6–7.5 and a general hardness of 4–15 dGH. A moderate water flow is preferred. An aquarium test kit can help you monitor these values.
Due to its specialist needs, the Otocinclus is best suited for fishkeepers who can provide a carefully planned setup. The Otocinclus is typically available in one standard form.
Otocinclus Habitat Setup
When setting up an aquarium for the Otocinclus, a moderate water flow best suits their natural preferences. Because this species occupies the mid-level and bottom zones, the aquarium layout should prioritise open swimming space in the centre of the tank for free movement and sufficient floor space with hiding spots among rocks, wood, or dense planting. Useful additions include smooth gravel or rounded substrate to protect their sensitive barbels, driftwood, which can serve as both a hiding place and a dietary supplement, an established tank with natural algae growth, as they depend on it as a primary food source, and dense planting to provide cover, break sightlines, and reduce stress. Browse smooth aquarium gravel options to find the best fit.
Otocinclus Compatibility Notes
Classified as peaceful, the Otocinclus is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. When choosing tankmates, boisterous or fast-moving tankmates may cause this species undue stress. Selecting tankmates that favour different water layers from the mid-level and bottom zones can help reduce competition and territorial overlap.
Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Otocinclus.
10 Gallon Standard
15 Gallon Standard
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
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Frequently Asked Questions About Otocinclus
How big does Otocinclus get?
Otocinclus (Otocinclus vittatus) typically reaches a maximum adult size of approximately 4 cm. They have a depressed body shape and a slow growth rate.
What tank size does Otocinclus need?
A minimum aquarium volume of 38 litres and a tank length of at least 45 cm are recommended for Otocinclus. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Otocinclus need?
Otocinclus thrives in freshwater only conditions with a temperature range of 21–26°C, a pH between 6 and 7.5, and a general hardness of 4–15 dGH. A moderate water flow is preferred.
Is Otocinclus peaceful or aggressive?
Otocinclus is classified as peaceful with an aggression score of 0 out of 10. They are generally well-suited to peaceful community tanks.
How many Otocinclus should be kept together?
Otocinclus is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Otocinclus have any special tank requirements?
Yes. Otocinclus benefits from established algae (otocinclus), plants - densely covered, smooth gravel (sensitive barbels), and driftwood (digestion/hiding) in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Similar Species
Bristlenose Pleco
Ancistrus cirrhosus
A highly popular, hardy, and relatively small suckermouth catfish. Excellent algae eaters that stay much smaller than Common Plecos, making them suitable for standard aquariums. They require dietary wood (driftwood) to aid in digestion and plenty of hiding caves.
Common Pleco
Hypostomus plecostomus
A heavily armored, nocturnal catfish famous for eating algae. However, they grow incredibly large, produce massive amounts of waste, and frequently outgrow standard aquariums. They require driftwood in their diet for digestion. As they age, they may become territorial or develop a taste for the slime coat of slow-moving, flat-bodied tank mates.
Whiptail Catfish
Rineloricaria sp.
A highly cryptic, peaceful, and extremely slender catfish that mimics a twig or dead leaf. They are excellent scavengers and biofilm grazers that require smooth sand and driftwood to thrive. They are completely non-aggressive, lack the heavy armor of larger plecos, and do well in peaceful community setups.
Striped Raphael Catfish
Platydoras armatulus
A highly robust, armored catfish native to the Amazon and Orinoco basins. Famous for their ability to produce audible squeaking or grunting sounds when distressed or defending territory. They are nocturnal scavengers that spend most of the day hiding in driftwood or caves. Note: Their rigid pectoral spines can easily become tangled in standard aquarium nets.
Chinese Algae Eater (CAE)
Gyrinocheilus aymonieri
Sold widely as a small, peaceful algae-eating juvenile, the Chinese Algae Eater (CAE) undergoes a drastic behavioral and dietary shift as it matures. Growing up to 25cm (10 inches), adults stop eating algae, become highly territorial, and are notorious for attacking slow-moving, flat-sided fish (like Angelfish, Discus, and Goldfish) to feed on their nutrient-rich slime coat. Best kept in fast-flowing river setups with robust, fast-moving tank mates.
Twig Catfish (Farlowella)
Farlowella acus
The Twig Catfish is an extremely elongated, master-of-camouflage suckermouth catfish from South America. True to its name, it mimics a dead twig perfectly, spending most of its time motionless on branches or plant leaves. It is a specialized aufwuchs and algae grazer that requires a mature tank, high oxygenation, and plenty of driftwood. They are completely peaceful but highly sensitive to fluctuating water parameters.