Otocinclus Catfish (Otocinclus macrospilus)

Otocinclus Catfish (Otocinclus macrospilus)

Tank-raised specimens of this classic nano fish are hard to find, but we have them! Compared to wild-caught specimens, tank-raised Otocinclus are generally more durable and well-suited to aquarium life.

Whether or not you have an algae problem in your tank, Otocinclus Catfish — also known as Otto Cats, Otos, or dwarf suckermouth catfish — are a fantastic addition to any freshwater community. These fish use their sucker mouths to graze algae from aquarium glass, plants, and decorations. They are widely considered one of the best algae-eating fish in the hobby, and groups of them make an effective cleanup crew.

Native to fast-flowing rivers in South America, Otocinclus Catfish thrive in aquariums with moderate to strong water flow, good filtration, and plenty of aeration.

Appearance & Behaviour

Otocinclus Catfish are small, peaceful fish with rows of armor-like plating along their bodies. Their neutral body colours, ranging from browns and grays to black, form attractive patterns. They are social, schooling fish that should be kept in groups of six or more.

These catfish grow to a maximum of 5 cm (2 inches) and are completely safe to keep with other non-aggressive fish, shrimp, snails, and live plants.

Feeding

While Otocinclus Catfish can mostly sustain themselves on algae, their diets can be supplemented with fresh vegetables such as cucumber or zucchini, algae wafers, or vegetable-based flake foods if algae is scarce in the aquarium.

What We Like About This Fish

• Widely considered the best algae-eating fish for freshwater aquariums

• Very social, schooling personalities

• Safe with plants

• Completely peaceful

• Rare, tank-raised specimens

Recommended Tank Parameters

• Temperature: 23–26°C (74–79°F)

• pH: 6.8–7.5

• KH: 2–10 dKH

• Minimum tank size: 10 gallons

Care Guidelines

• Diet: Mostly algae; supplement with fresh vegetables, algae wafers, or vegetable-based flakes if needed

• Social behaviour: Peaceful, schooling/shoaling

• Origin: South America

• Average adult size: 3.8–5 cm (1.5–2 inches)

• Average purchase size: 2.5–3.8 cm (1–1.5 inches)

Sample photo is for reference only. Exact fish may vary in size and colour.