I have a 10 gallon tank with 4 guppies, 3 mollies and 1 cory. I've heard corys do better in groups, but I think my tank has quite a few fish already. They don't take up much room, tehre's a lot of open space for them to swim around, and they are all small fish, but it just sounds like a lot to me. My question is, can I safely add 1-2 more corys so my lone cory is happier?