Ourastigma Cory

Geographic Origin and Biotope: Native to South America, specifically endemic to the Purus river basin in western Brazil. Resides in small watercourses, isolated oxbows, and streams (igarapés) characterized by weak flow and thick mattresses of foliage, under the dense shade of the Amazon canopy.

Taxonomy and Morphology: Belonging to the large group of long-snouted Callichthyidae. It presents a tapered and markedly hydrodynamic profile. A specimen of respectable dimensions: stably reaches 6 cm (2.4 inches) as an adult.

Social Behavior: Extremely gregarious. Forced into loneliness, it collapses prey to panic, stopping feeding. Categorically requires schools of at least 6-8 individuals to manifest the reassuring collective patrolling of sandy areas in broad daylight.

Coloration and Sexual Dimorphism: The name "ourastigma" alludes to the pronounced dark and rounded spot ("stigma") placed at the base of the caudal fin ("oura"). The rest of the slender body is light, cream/pinkish, crossed by faded streaks and spots descending from the back. Females stand out for their width and visceral roundness.

Aquarium Setup: The long snout serves to sink into the sand, therefore the bottom must be strictly composed of fine silica sand. Thick tufts of Echinodorus at the edges and vast shady "roofs" composed of intricate woods (Mangrove) are necessary to guarantee it total tranquility.

Diet and Feeding: Specialist in benthic predation. The standard diet must be satisfied through highly proteinaceous rapidly sinking granules or tabs. Indispensable, to maintain vigor, to alternate tri-weekly with frozen Tubifex and red Bloodworms.

Water Quality: Species very susceptible to water degradation, primarily to nitrates on the bottom. Maintain temperatures between 22 and 26°C (72-79°F). The ideal pH stands on neutral-acidic (6.0 - 7.2) combined with water of modest hardness (GH 2-12). Parsimonious but rigorous siphonings are recommended.

Compatibility and Tankmates: Perfectly shares medium biotopes with peaceful Tetras (Neon tetras, Rummy Nose), small Loricariids (Otocinclus) and schools of Carnegiella on the surface. Terrible cohabitation with aggressive Cichlids, titanic loricariids, or edgy Loaches that would dominate the food.

Aquarium Reproduction: "Monsoon" style reproduction: must be triggered with drastic and massive water changes (cold RO water). The rite in T-position culminates with the deposit of large clear and resistant eggs on smooth furnishings or leaves. Imperative to remove the brood to evade parental cannibalism.

Risks and Diseases: Crushed granular bottoms inevitably amputate the long whiskers triggering fulminant bacterial necrosis. Exposed to Copper (Cu) and Malachite green (in standard medicines), it dies of intoxication before the primary disease is resolved.