I believe they are Corydoras Aeneus or intact not a Corydoras at all the emerald brochis (Corydoras splendens) however they are very closely related and they are in the same family.
According to Fishbase, this fish, which used to be called Brochis splendens, has now been moved into the genus Corydoras, as animal_expert says. It is a very beautiful fish under the right conditions.
