I'm looking for some hardy yet, smaller species of Corydoras for my 20 gallon tank. I currently have 3 platies in the tank. Correct me if I'm wrong but I don't think I have enough room for a school of 6 Corydoras that are 2-3 inches in size.....? There are not too many small species of Cories except for pygmies but I have heard some mixed reviews on them...