Hi we have a malawi electric yellow (think hes a male) in our large tank with green sevs, angels, a geo and some gouramies.But he is starting to get too agressive for the other fish. So i thought i would set up a smaller tank just for him and maybe another electric yellow, also if i do this i would be able to give him the right ph and temp etc for his species, WHat would the smallest tank that i could house him in with a female? Thanks