Dwarf Corydoras

Osteogaster rabauti is a small species of catfish, with adults typically growing to a length of 55 millimetres (2.2 in) to 65 millimetres (2.6 in). It is sexually dimorphic, with sexually mature females tending to grow larger, broader, and deeper-bodied than males. As with all corys, O. rabauti is completely scaleless, and is instead covered with bony plates known as scutes.

Osteogaster rabauti is native to the Upper Amazon, Solimões, and Rio Negro basins in South America. It is found in a pH range of 6.0 to 8.0, in depths between 2 metres (6.6 ft) and 25 metres (82 ft), and in tropical temperatures of 25 °C (77 °F) to 27 °C (81 °F). It primarily inhabits floodplain lakes, oxbow lakes, and riverine habitats. While the full extent of its distribution is somewhat unclear, it is known to inhabit Brazil and Peru, and possibly Colombia as well. The type locality is a "tributary of [the] Amazon River, 7 days by river boat from Manaus, 3°06’S, 60°00’W, Amazonas, Brazil". Osteogaster rabauti is also known to have been introduced to the Philippines as an ornamental fish in 1996. However, it is unknown whether it has successfully established itself in the years following, and if so, what impact it has on the environment, if any.

Osteogaster rabauti is a peaceful and gregarious fish, and well-suited to a community aquarium. Care should be taken not to house them with aggressive fish, as they may get harmed by O. rabauti's venomous spines if they try to nip them. An unusual behavior that Osteogaster rabauti exhibits is occasionally rising to surface of the water and taking in gulps of air before submerging. This is not necessarily indicative of oxygen deprivation, but rather because O. rabauti and other corys are facultative air-breathers, similar to Siamese fighting fish and tarpon. They possess a heavily modified intestine, which allows them to take in atmospheric oxygen and survive in low-oxygen environments.

Like several other related species, such as Hoplisoma adolfoi and H. panda, Osteogaster rabauti secretes a mild venom from the axillary glands at the base of each pectoral-fin spine in order to protect itself from predators. When stiffened, these spines are capable of penetrating human skin and causing significant pain in conjunction with the venom.

Osteogaster rabauti is known and sold by a wide variety of common names, including the rust corydoras, Rabaut's corydoras, Myers's corydoras, dwarf corydoras, iridescent corydoras, orange-red corydoras, Rabaut's catfish, rusty cory, Rabaut's cory, and iridescent cory.