Big-Spot Otocinclus (Otocinclus macrospilus) Care Guide
Otocinclus macrospilus is a tiny dwarf suckermouth catfish from the upper Amazon, a shy, shoaling algae grazer best kept in groups of six or more in mature tanks.
Overview
Otocinclus macrospilus is a dwarf suckermouth catfish of the family Loricariidae (subfamily Hypoptopomatinae), commonly called an "oto." It is one of the smallest aquarium loricariids, reaching only about 3.5 cm. It is frequently mislabelled in shops as O. affinis or O. vittatus.
Taxonomy
- Family: Loricariidae
- Scientific name: Otocinclus macrospilus
- Subfamily: Hypoptopomatinae
- Common synonyms: Macrospilus Oto
Habitat
The species is endemic to the upper Amazon, principally in Peru, with some records extending into Colombia and Ecuador. Otos live in shoals in small streams and well-oxygenated river margins, clinging to wood, stones and broad-leaved plants where they graze the surface film. The genus possesses an air-breathing duct, an adaptation to low-oxygen conditions.
Tank requirements
- Minimum tank volume: 60 L (16 gal)
- Adult size: 3-4 cm (1.2-1.6 in)
- Temperature: 22-26 °C (72-79 °F)
- pH: 6-7.5
- GH: 2-12 °dGH
- Group size: ≥6 individuals
- Lifespan: 8-12 years
Diet
The diet is algae-based, dominated by diatoms and aufwuchs (the film of algae and micro-organisms on submerged surfaces). It does best added to a mature, planted tank with a steady supply of soft green algae and biofilm; vegetable foods such as cucumber, courgette and spinach, plus algae wafers, supplement this. Small live or frozen foods are taken only sparingly.
Compatibility
The fish is very shy and retiring and is easily outcompeted for food, so it needs peaceful tankmates. It is a strongly social shoaler and should be kept in groups of at least six. It is plant-safe and combines well with small tetras and Corydoras.
Breeding
Spawning occurs in a T-position similar to Corydoras, with eggs scattered among plants and on the glass; the genus lays adhesive eggs and does not guard them. Large weekly water changes with cooler water appear to help trigger spawning.