Otocinclus
Otocinclus sp.
Minimum Tank
10 Gallons
Adult Size
2 inches
Temperature
72-79°F (22-26°C)
pH Range
6.0-7.5
Lifespan
5 years
School Size
6+ fish
About Otocinclus
The otocinclus, affectionately called the oto, is a tiny catfish from the rivers and streams of South America, primarily found in southeastern Brazil, Argentina, and Venezuela. At just 1-2 inches, otos are among the smallest catfish species and are cherished for their tireless algae-eating habits. Their streamlined, sucker-mouthed bodies are perfectly adapted for clinging to smooth surfaces while rasping off thin films of algae. Otocinclus are social, gentle fish that pose no threat to even the smallest shrimp or fry. They are widely regarded as the best algae-eating fish for planted tanks, as they consume diatoms and soft green algae without damaging delicate plant leaves.
Care Requirements
Tank Setup
- • Minimum 10-gallon tank required
- • Temperature: 72-79°F (22-26°C)
- • pH: 6.0 - 7.5
- • Category: Catfish
Diet & Feeding
- • Diet type: Herbivore
- • Feed 1-2 times daily
- • Varied diet recommended
Tank Mate Compatibility
Compatible With
Avoid Keeping With
Care Tips
Expert Tips
Otocinclus have a notoriously high mortality rate shortly after purchase due to starvation and stress during shipping. Buy only active, well-fed specimens with rounded bellies. Keep them in groups of at least six in a mature tank with established algae growth. A newly set up tank without biofilm will not sustain them. Supplement their diet with blanched zucchini, cucumber, and sinking algae wafers, especially if the tank's algae supply runs low. They need clean, well-oxygenated water at 72-79°F with zero ammonia and nitrite. Never add them to an uncycled or immature tank. Otos are sensitive to medications, so research treatments carefully.
Quick Facts
38L
Min Tank (10gal)
5cm
Adult Size (2")
5yr
Lifespan
6+
Min School
Build Your Perfect Community Tank
Find compatible tankmates for your Otocinclus
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Tank Mates for Otocinclus
Species from our database with overlapping water parameters, compatible temperaments and a realistic shared tank size.
Cardinal Tetra
Paracheirodon axelrodi
moderate · 15+ gal
Amano Shrimp
Caridina multidentata
easy · 10+ gal
Blue Velvet Shrimp
Neocaridina davidi var.
easy · 5+ gal
Bleeding Heart Tetra
Hyphessobrycon erythrostigma
moderate · 20+ gal
Similar Care Level
Other moderate-care species that suit a comparable setup.
Frequently Asked Questions
What size tank does a Otocinclus need?
A Otocinclus needs a minimum tank size of 10 gallons (38 litres). They should be kept in schools of at least 6.
What water parameters does a Otocinclus need?
Otocinclus thrive in water between 72-79°F (22-26°C) with a pH of 6.0-7.5.
Are Otocinclus easy to care for?
Otocinclus are considered moderate to care for. They are peaceful fish with a lifespan of about 5 years.
How big do Otocinclus get and what do they eat?
Otocinclus reach about 2 inches and are herbivores. Otocinclus have a notoriously high mortality rate shortly after purchase due to starvation and stress during shipping. Buy only active, well-fed specimens with rounded bellies. Keep them in groups of at least six in a mature tank with established algae growth. A newly set up tank without biofilm will not sustain them. Supplement their diet with blanched zucchini, cucumber, and sinking algae wafers, especially if the tank's algae supply runs low. They need clean, well-oxygenated water at 72-79°F with zero ammonia and nitrite. Never add them to an uncycled or immature tank. Otos are sensitive to medications, so research treatments carefully.