Yeah, in nicer language, I would say that the three triggers should never be housed in a 30 gallon tank to begin with because it is an improper aquarium for them to live and grow. They may be living now, but they will not be for much longer.
A 30 gallon really is not the proper tank for aggressive fish. A 30 gallon is more of a reef tank because aggressive fish need huge tanks, as they grow huge. This is one reason why they are able to remain "aggressive" fish. If they did not get big, no one would consider them aggressive because they could be easily bullied by many more bigger things.