The OP has 10, where I had about 8, and mine were in a 45 gallon tank. The first week or so they stayed pretty well together, but as they got totally acclimated they started spreading out a lot more. When eating, they ate "family style" - all together, lots of interaction among them. But, after dessert and coffee they went back to being all spread out. I think snoopy65 is right.