Giant Otocinclus

Geographic Origin and Biotope: Widely distributed in Amazonian rivers, frequents sandbanks and submerged branches at the margins of medium-slow currents in wooded areas or flooded forests.

Taxonomy and Morphology: Elongated and unusual shape. The eyes are positioned very low on the sides of the flattened head (to look down while clinging to trunks). It reaches 10 cm (4 inches), a remarkable size for a hypoptopomatine. Exceptionally wide and expanded sucker mouth.

Social Behavior: Extremely peaceful, harmless, and constantly busy. Completely ignores other inhabitants. Loves to rest vertically attached to the glass or, even better, parallel on thick smooth branches and roots.

Coloration and Sexual Dimorphism: Silver gray to mottled olive brown. The ventral part is white. No marked dimorphism to the naked eye; mature females appear larger in the belly when viewed from below.

Tank Setup: 80-100 cm (30-40 inches) aquarium with large soft leaves (Echinodorus) and countless smooth branches. Absolutely lethal to insert them in new or aseptic aquariums without algae or bacterial films. Real wood mandatory.

Feeding and Diet: Very strict herbivore. Tireless algae-eating machine. Shaves microflora and biofilm. Being large, it will clean the glass but demands daily blanched vegetables (thick zucchini) so as not to starve to death. Rejects meat.

Water Quality: Clean water, very low in nitrates. Sweet pH 6.0-7.4, docile hardness GH 2-12. Classic forest temperature between 23 and 27°C (73-80°F), well aerated in summer.

Compatibility and Cohabitation: Golden model for planted aquariums of characins, angelfish, corydoras, or dwarf cichlids. DO NOT INSERT with dominant bottom fish that would take away its soft food or huge fish that would swallow it whole.

Aquarium Reproduction: Free-leaf spawning species. They lay adhesive eggs on the walls or on large broad leaves; they show zero to non-existent parental care (often eaten by roommates).

Risks and Diseases: High early death rate for starved imported wild fish. Make sure at the store that the abdomen is full and smooth, never concave in an inverted 'V' shape.