Ottocinclus

Overview

The Otocinclus / "Oto" (Otocinclus macrospilus) is a tiny, peaceful algae-eating catfish that is essential for planted tanks. They are one of the best algae grazers for glass and plant leaves. Must be kept in groups and in mature aquariums with established algae growth.

Water Parameters

• Temperature: 22–27°C (72–81°F)
• pH: 6.0–7.5
• Hardness: 5–15 dGH

Tank Setup

• Minimum tank size: 55 litres for 6+
• Substrate: Any; they primarily graze on glass, leaves, and hardscape
• Decor: Planted with driftwood; mature tank essential (they need algae/biofilm to eat)
• Note: Only add to tanks established 2+ months with visible algae growth

Diet

• Base: They graze on natural algae and biofilm — supplemental algae wafers if needed
• Treats: Blanched vegetables (zucchini, cucumber), spirulina wafers
• Note: They can starve in new tanks without established algae — ensure food source

Temperament & Tank Mates

• Temperament: Peaceful, shy schooling fish
• Best companions: All peaceful community fish; they are ignored by tank mates
• Schooling: Minimum 6; they feel safe in groups

Breeding

• Difficulty: Difficult; scatter spawner
• Note: Breeding in captivity is rare but possible with very stable conditions

Common Issues

• Starvation is the biggest risk — ensure mature tank with algae
• Stress from being added to new, algae-free tanks often leads to death
• Quarantine new additions — they are often stressed from transport
• Lifespan: 1–3 years