so when i first got my clowns they picked this one rock in the tank to be theirs. they're always cleaning it and if my hand would go anywhere near it they would sort of swim around me. Recently they've become much more aggressive. I can't stick my hand anywhere in the tank without them INSTANTLY jetting over and attacking my hand. They do it with a significant amount of force too. They do the same thing to the algae scrubber when i'm cleaning the tank. the largest one is about 1 3/4 at most so i on't think they are sexually mature.