Otocinclus

The Otocinclus, affectionately known as the "Oto Cat" or "Dwarf Sucker," is a tiny algae-eating catfish that has earned a reputation as the ultimate nano tank cleaner. At just 1.5-2 inches in length, these diminutive fish pack a powerful algae-eating punch, tirelessly grazing on glass, plants, and decor to keep tanks spotless. Native to South America, particularly Brazil and Argentina, they inhabit clear streams with plenty of vegetation. Otocinclus are peaceful, social fish that must be kept in groups to feel secure and display their best behavior. They have a unique appearance with their sucker mouths and streamlined bodies. While they are excellent algae control agents, they can be challenging to keep initially due to their wild-caught nature and specific dietary needs. However, once established and well-fed, they are hardy and rewarding additions to peaceful community tanks.

Care Requirements

Tank Setup

Otocinclus need established tanks with algae growth and plenty of hiding spots. Heavily planted tanks are ideal. Use driftwood, rocks, and dense vegetation like java moss and cryptocoryne. Avoid new tanks without established algae. Gentle filtration is essential; they dislike strong currents. Provide hiding spots throughout the tank to reduce stress.

Water Quality

• Temperature: 72-79°F (22-26°C)
• pH: 6.0-7.5
• Water Hardness: Soft to moderate (2-15 dGH)
• Ammonia/Nitrite: 0 ppm
• Nitrate: <20 ppm

Stable, pristine water conditions are crucial. They are sensitive to poor water quality and parameter fluctuations.

Feeding

Specialized algae eaters that require supplemental feeding:

• Natural algae and biofilm (primary food source)
• High-quality algae wafers (break into smaller pieces)
• Blanched vegetables: zucchini, cucumber, spinach daily
• Supplemental feeding is essential as they often starve in clean tanks

Feed vegetables daily, especially in newer or cleaner tanks. They cannot survive on algae alone in most home aquariums.

Behavior & Compatibility

Peaceful and shy schooling fish that must be kept in groups of 6 or more, ideally 10+. They establish pecking orders and feel secure in numbers. Active throughout the day grazing on surfaces. May hide initially but become more confident over time. Compatible with all peaceful nano fish and invertebrates. Avoid large or boisterous tank mates that outcompete them for food.

Common Health Issues

1. Starvation: Most common cause of death; ensure supplemental feeding
2. Internal parasites: Common in wild-caught specimens; quarantine essential
3. Bacterial infections: Secondary to stress and poor water quality
4. Ich: Treat with standard methods (scaleless fish - use half dose)

Breeding

Difficult to breed in captivity but possible. They are egg scatterers that lay eggs on plants, glass, and decor. No parental care. Breeding is rare in community tanks. Requires pristine water and specific conditions. Most available otos are wild-caught.

Tips for Success

• Buy only from established tanks at the store; never buy pale, skinny specimens
• Quarantine for 2-4 weeks; most losses occur in first month
• Keep in groups of 6+ for security and best behavior
• Feed vegetables daily, especially in clean tanks
• Add only to established tanks with algae growth (3+ months old)
• Avoid new tanks or recently cycled tanks
• Provide plenty of hiding spots to reduce stress
• Monitor body condition; emaciated otos usually indicate starvation