Some sunnies are agressive. There are a ton of different types of sunfish and those are both green sunfish. Greens happen to be one of the most agressive sunnies.
Cool tank...Im hoping to get a 75 real soon and make it a sunny tank. Put a few crawfish in it and catch minnows for them....Had a tank like this. It was great but then it flooded my living room...still love the fish though