Otocinclus (commonly known as "Otos" or "Dwarf Suckers") is a genus of small, peaceful catfish from South America highly prized in the aquarium hobby for their unmatched ability to eat soft algae and diatoms.
Core Characteristics
Size & Appearance: They are among the smallest catfish, typically reaching only 1.5–2 inches (4–5 cm). They feature armored plating and a specialized suckermouth for clinging to surfaces.
Behavior: Unlike many catfish, Otos are diurnal (active during the day) and extremely social. They should be kept in schools of at least 6 or more to reduce stress and encourage natural grazing.
Unique Biology: They possess an esophageal diverticulum that allows them to breathe air, which can help them survive in low-oxygen environments.
Aquarium Care Essentials
Diet: Primarily herbivores that specialize in soft green algae and brown diatoms. In clean tanks, they must be supplemented with algae wafers, sinking pellets, or blanched vegetables like zucchini and spinach to prevent starvation.
Tank Setup: They thrive in mature, heavily planted tanks with driftwood and stable water conditions.
Temperature: 72–82°F (22–28°C).
pH: 6.0–7.5 (slightly acidic to neutral).
Filtration: High-quality filtration is critical, as they are sensitive to ammonia and nitrites.
Tank Mates: Excellent for community tanks with other peaceful species like Tetras, Rasboras, and Dwarf Shrimp. Avoid large or aggressive fish that may see them as prey.
