Corys are members of the Corydoras genus from south america and are popular in the aquatic hoby, doing especially well in the community aquarium. Corys typically measure around three to seven centimeters in length when fully grown, they get along well with other species and are not at all aggressive. It is recommended to keep Corys in groups of six or more, as they are shoaling fish. Corys are bottom feeders, so they should be offered flake foods, which do sink, sinking pellets, sinking tablets and supplements of live and frozen foods . They also enjoy fresh veg to be added to the aquarium such as cucumber, also relished by plecs and freshwater shrimp.
Many Corydoras species have been described by science; in addition, many variants exist. Several hundred Corydoras species are not yet classified by science, but kept by aquarists. These species are given C Numbers, there are 131 C Numbers currently.
Corydoras are native to the rivers of South America such as the Amazon, therefore most of them prefer soft, acidic water. However, they can tolerate a wide range of water conditions. They are very sensitive to aquarium salt, though, and do not do well in fish tanks with high nitrate levels. This ion leads to the infection of the barbels, which will shorten and become useless. The barbels may also be affected by constant contact with a sharp substrate. These are easy fish to keep, being peaceful, small, good at cleaning up leftover foods, though their keeper should ensure that they get their own food, hardy, active, and entertaining.
Though all Corydoras species are diurnal, most exhibit some level of activity during the nighttime.
Albino Corydoras, C. aeneus, are frequently injected with bright dye via a needle and sold in aquariums. This practice is known as fish juicing, this is a cruel method and such fish should be deliberately avoided.