yellow tangs fin ripped

ok so i have a 90 gallon reef tank with a sailfin tang a yellow tang a pixy hawk two damsels and a maroon clown and a percula, today i noticed the yellow tang had a small bite rom his fin, its not very large hardly even noticeable but could this be a result of agression in the tank? the only fish thats really agressive is the hawkfish and he picks on my poor little maroon whose fins are constantly torn. will they heal? or just worsen? most other fish iv ehad that got their fins ripped eventually died. but he is doing fine and doesnt seem to notice he acts normal just his ripped fin. any help would be great

 

Any one of those fish have the ability to become aggressive. Just because you don't see it doesn't mean that aggression doesn't happen. They could very well be fighting when you're not watching them.