Otocinclus Catfish

 Quick Care Facts

• Care Level: Easy   • Temperament: Peaceful   • Maximum Size: 2"
• Minimum Tank Size: 30 gallons   • Water Conditions: 74-82° F, KH 6-10, pH 6.5-7.5
• Diet: Herbivore   • Origin: South America   • Family: Loricariidae
• Species: Suckermouth Catfish   • Aquarium Type: Community

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Otocinclus Catfish (Otocinclus sp.) originate from South America where they are found living in small streams, tributaries and on the margins of larger rivers. They live clinging to substrates and plants using their mouth as a sucker, and feeding on algae growth on submerged wood & roots, stones, and the leaves and stalks of aquatic plant life.

They inhabit water ways that have well oxygenated water and prefer areas where the water flow ranges from gentle to moderate. The water in the Otocinclus Catfishs native environment are clean and contain very low levels of dissolved nutrients.

Otocinclus Catfish live in groups of individuals called schools, in which the school will inhabit a relatively small area of a water way provided that there is adequate food sources. They generally only migrate substantial distances if they are forced to by receding waters caused by drought or seasonal rains.

Otocinclus Catfish are found within the aquarium hobby under a wide variety of common names, which include: Oto Catfish, Otos, Ottos, Dwarf Suckermouths, Dwarf Oto, Dwarf Ottos, Dwarf Suckers, Otto Cats, Pygmy suckermouths, Macrotocinclus affinis and Otocinclus affinis.

The wide range of names for this species is somewhat of a testament to how popular they are with aquarium hobbyists who keep planted community aquariums. Otocinclus Catfish are considered one of the super stars of any algae control team, they excel at consuming algae from plant, wood and rocks.

They are especially coveted by those with planted aquariums, as they can remove algae from even the most delicate plants without causing any damage to leaves. Probably the greatest testament to the Oto Catfishes algae eating prowess was that they were often included in planted aquariums designed by the late Takashi Amano, where they were paired with Amano Shrimp and Nerite Snails.

In order to successfully care for Otocinclus Catfish, hobbyists need to focus on three things: stable water conditions, established algae growth and suitable tank mates. Otocinclus Catfish are not a suitable day one fish species, they should be added to aquariums that are well established, this will provide them more stable water parameters and some existing algae growth on which to feed.

While not absolutely required, they will do best in aquariums with plenty of live vegetation, soft sandy substrate and some smooth rocks and drift wood or wood root. Lastly, Otocinclus Catfish are a very peaceful species that needs to be kept with other peaceful community fish and invert species, like Tetra, Discus, Rasbora and ornamental shrimp.

They will not do well with more aggressive species like Cichlid fish or ornamental crayfish. In addition to an established aquarium, algae growth and peaceful tank mates, the Otocinclus Catfish requires gentle water flow, warm slightly acidic water and areas of diffused lighting.

The Otocinclus Catfish is a herbivore who requires that a large portion of its diet comes from naturally occurring algae growth, which is essential for the Oto Cat to maintain a healthy immune system. They consume naturally occurring algae from within the aquarium by grazing on the aquarium glass, substrate, plants, rocks and driftwood.

In cases where the aquarium does not have enough algae growth to support the Otocinclus Catfish, they will also consume blanched vegetables like zucchini or squash, sinking algae wafers, or other similar herbivore foodstuffs. However, when kept in well established planted aquariums the hobbyist should rarely if ever need to provide supplemental feedings.

Hobbyists should be able to gauge whether sufficient food is available within the aquarium by visually identifying natural algae growth within the tank and through visual inspection of the Otocinclus Catfish, looking for a properly shaped plump body.