That does look like a male/female combination. Aggression COULD abate a bit with time. THe problem is that you never know when it is going to flare up again. That is an excellent size aquarium for breeding. If you can resist the urge to put in additional fish, you should get them to breed since it appears they are attempting to pair bond. My advice would be to ge a divider now, and cut holes so they can go back and forth. Eventually the male will become larger than the female and not be able to make the trip back and forth. While they are still small you could put in a few smaller target fish...like fast swimming Danios or Metynsis.
