Red-Fin Otocinclus

Geographic Origin and Biotope: South Brazilian species from coastal basins (Paraná, Santa Catarina). Inhabits clear, cold streams flowing over rocks, gravel, and sand, with strong currents and dense marginal vegetation washed by the water.

Taxonomy and Morphology: Dwarf Loricariid. Similar to a large, stout, and compact Otocinclus. Reaches barely 5 cm (2 inches). Unlike Otocinclus, it possesses a tiny adipose fin (small fleshy bump on the back before the tail). Inferior sucker mouth suitable for continuous scraping.

Social Behavior: Extremely lively for a suckerfish. Always in diurnal motion, methodically grazes rocks and large leaves. Obligate gregarious fish: needs schools (minimum 6-8) or will die of stress. Harmless to the rest of the community.

Coloration and Sexual Dimorphism: Magnificent brown/gold or gold-dusted sand base, dark marbled. The tail and dorsal fin have spots (hence maculicauda) of a beautiful brick orange or bright blood red. Mature females noticeably rounder on the belly than slim males.

Tank Setup: Small group suitable for tanks from 60 cm (24 inches) up. Set up in 'stream' style: intricately branched wood, scattered river pebbles, compact vegetation, and a very STRONG CURRENT. Insert exclusively in mature aquariums (over 6 months old) and saturated with natural soft micro-algae.

Feeding and Diet: Aufwuchs and biofilm. Without the organic film of aseptic glass, it dies. Supplement the diet by offering sunken cucumber rounds and vegetable spirulina flakes moistened and stuck to stones.

Water Quality: THE CRITICAL FACTOR IS THE COLD: coming from the extreme south of Brazil, it does not tolerate or quickly wastes away in tropical heat. Vital temperature between 20°C and 25°C (68-77°F) maximum, perfect without a heater in the house. Very demanding in oxygen, with tolerant pH 6.5-7.5.

Compatibility and Cohabitation: Golden roommate for small cold-stream fish like neons, panda corydoras, small characins, and cyprinids (danios and rasboras). Strictly prohibited with large cichlids and hot Amazonian Discus tanks.

Aquarium Reproduction: Difficult to stimulate on purpose, but they spawn on glass or broad leaves in the presence of hyper-abundant food. As with corydoras, no post-spawning parental care.

Risks and Diseases: Lethal fulminating mortality if inserted in hot tanks over 27 degrees (80°F) (suffocation by organic anoxia) or if inserted in sterile starter cubes without massive algae production on the glass.