The Clown Trigggerfish are actually pretty territorial and when you swim near their "nest" they will swim towards you and attack you. I know this because I swam too close to a few and they swam over and bit my leg..
Perhaps they can make the Triggerfish more aggresive in the game. They're very passive right now..
(On a side note, sardines aren't tropical are they? It's so odd seeing them...)