Callichthys callichthys is the nominate species of the family Callichthyidae and inhabits slow-moving, often stagnant and oxygen-poor waters across a vast range from the Amazon to the Rio de la Plata. Like many callichthyids, it uses a modified intestine to extract oxygen from gulped air, an adaptation that allows it to survive conditions that would quickly kill most fish. In the aquarium it is an undemanding, heavy-bodied catfish that spends most of its time sifting substrate for edible matter.
In the wild, males construct floating bubble nests beneath surface vegetation and guard the eggs aggressively. This breeding behaviour can be replicated in captivity when the fish are well fed and water conditions are stable. The species is tolerant of a wide pH and temperature range, making it highly forgiving for aquarists of all experience levels.
Callichthys callichthys is best housed with equally robust tankmates that can tolerate its active nocturnal foraging. It will eat almost anything offered — sinking pellets, frozen bloodworm, worms, and vegetable matter — and quickly becomes a bold, interactive resident of the bottom third of any large community aquarium.
