I have been told by almost everyone in any lfs that silver dollars are aggresive and are very nippy, I personally have had a small group of silver dollars in my 77 gal community tank for a long time now and have never found them to be aggresive but acually very shy and peacfull esspecialy given how mutch bigger they are then the rest of my fish. However yesterday I was peacfully obbserving my tank when I noticed they seemed to be patrolling the tank and any fish they came into contact with was emediatly chased away, then they started to chase around one of my Bosemani rainbows... is this normall, are they accualy an aggresive fish and for some reason I never noticed before? They seem to have stopped doing it now for some reason... whats going on?