Petracini's cory

About

Found in northwestern Argentina, this small armored catfish, Corydoras petracinii, is almost certainly not available in the aquarium trade and is unlikely to be collected commercially given the remoteness of its natural habitat. It belongs to the family Callichthyidae, the group commonly called armored or mailed catfishes because their bodies are covered in rows of bony plates rather than ordinary scales. What makes this species physically distinctive among its relatives is a suite of adaptations for life among rocks in fast-flowing water: shorter fin spines, a shallower body profile, ventrally angled pectoral fins, and a muted, blotchy color pattern that provides camouflage against stony substrate. The flanks carry five to seven squarish dark blotches running along the junction of the body plates, while the caudal fin shows three or four irregular banded markings. The eyes are notably small. Like other corydoras, it is a facultative air breather, using a specialized, highly vascularized section of intestine to extract oxygen directly from the atmosphere. A behavior you'd see as occasional surface gulps. Also worth knowing for any handler: the stiffened pectoral-fin spines can pierce skin, and secretions from glands at their base may cause a painful, possibly venomous reaction. Handle any cory with care.