I wanted to add some cories that stay small and are good in a community tank. Which kind out of these two should I add: Corydoras hastatus - Dwarf Corydoras or Corydoras habrosus - Dainty Corydoras? And what is the minimum number to keep them happy in a school? And another question is the Corydoras habrosus the same as a corydoras pygmaeus? Tanks specs can be seen in signature. Thanks.