The pygmy corydoras (Corydoras pygmaeus) is a small tropical fish that is native to South America. It is one of the smallest fish in the corydoras pygmaeus family, Callichthyidae. It has a pale tan or olive color on its body. 
Pygmy corydoras are peaceful schooling fish that are compatible with most nano aquarium animals. They are a great choice for aquarists interested in nano fish. They are not suitable for the general community aquarium because they may be intimidated by or preyed upon by larger tankmates. 
Pygmy corydoras are hardy and do well in tanks of at least 10 gallons.  They often shoal, which is rare for a bottom-dweller. They may even swim in groups in the mid-levels of the tank. You should keep them in groups of at least four or more, but eight is recommended. 
Pygmy corydoras are bottom dwellers that help clean the tank by feeding on leftovers. However, they don't make for the best cleanup crew because of their diminutive size. They really can't take up a lot of uneaten food