Otocinclus Dwarf Sucker Catfish Macrotocinclus Affinis 2cm

Overview

The Otocinclus or Dwarf Sucker Catfish is a tiny, slim, sucker-mouthed loricariid with a dark lateral stripe over a mottled olive back. Otocinclus (Macrotocinclus) affinis comes from streams around Rio de Janeiro, Brazil. It is prized as a gentle algae grazer for mature planted tanks and suits careful beginners upwards.

• Adult Size: Around 4–5 cm (1.6–2 in)
• Lifespan: 3–5 years

Origin

• Native to: Rio de Janeiro state, south-eastern Brazil
• Habitat: Clear, well-vegetated streams with slow to moderate flow

Feeding

• Diet: Herbivorous, algae and biofilm grazer
• Preferred Foods: Soft green algae, biofilm, algae wafers, blanched courgette, spinach, Repashy gel
• Feeding Habits: Grazes all day; supplement daily if algae is scarce

Tank Mates

• Best with: Tetras, rasboras, pygmy corys, shrimp, snails, small rainbowfish
• Avoid: Cichlids, large or aggressive fish, anything that eats small fish

Aggression & Behaviour

• Temperament: Very peaceful
• Territoriality: None

Experience Level

• Difficulty: Intermediate
• Challenges: Delicate on import; starves in new, algae-free tanks

Water Parameters

• Water Type: Freshwater, soft to moderately hard, clean
• Temperature: 20–26°C (68–79°F)
• pH: 6.0–7.5
• Hardness: 5–15 dGH
• Flow: Moderate, well oxygenated
• Tank Size: Minimum 60 litres; mature planted tank for a group of six

Final Notes

Only add to a well-established tank with algae and biofilm already present, and acclimatise slowly as new arrivals are often thin. Keep a group of six or more; solitary fish hide and fade. Females are broader when viewed from above. They are most active at dusk, appreciate driftwood and broad-leaved plants to graze, and are sensitive to copper medications. A healthy, well-fed group keeps leaves and glass spotless.