Oto – Otocinclus macrospilus

Oto - Otocinclus macrospilus

  • pH: 6-7.5
  • gH: 1-12dGh
  • Temperature: 21-26C
  • Maximum Size: 3.5cm
  • Minimum Tank Size: 40 litres, 45x30x30cm

The Oto is the smallest of the “pleco” family at 3.5 cm maximum. They are found in the wild in Peru, Colombia and Ecuador at the edges of the Amazon and its tributaries amongst the plants.


Otocinclus macrospilus does better in a group of six or more of its own kind and should be kept with very peaceful species such as the smaller tetras and rasboras to allow it to compete successfully for food.

Housing and Feeding

Otos appreciate a sand substrate and plenty of live plants, including broad-leaved plants whose leaves it will rest on.

In the wild, otos feed on algae and should not be introduced to new tanks until substantial algae growth is present. Prepared foods such as algae wafers will be taken eventually, but new specimens, if wild caught, may refuse commercial foods at least initially. Fresh vegetables such as courgette should be offered regularly.


Breeding of this fish in the aquarium is rare, but when it does occur follows the pattern of corydoras spawning behaviour. Fry need plenty of algae available as they are extremely small and unable to take larger foods initially.


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