Most of my adults tend to hang around one another. They burrow into the same holes and hide under the same logs. There's always groups of them together in my pen, and its not lack of space either as there is plenty of room for them to avoid one another.
My babies don't fight at all unless they're trying to pull food out each other's mouth. They're some what crowded, since I have 25 of them in a 30 gallon tank right now. There's still alot of room for them thoough.