Aggressive clown towards my lion fish

[brenjada]

We just got a new and our first trigger fish. He is attacking our large Lion Fish. Note my lion fish is about 10" long. The trigger chewed up all his fins. They are very short and this happened over the last two days. I am taking the trigger back to the fish store, but I want to know if my lion fishes spines, webs, fins (whatever you want to call them) grow back or will he eventually die because of this?

 

[saxman]

As you've found out, "reef" triggers and lions don't mix, nor do large species angels or puffers with lionfish. Definitely a hard lesson learned...research is your best friend.
It depends on the severity of the damage...if the fins aren't chewed into the "quick", they will likely regrow, but it may take some time...or the fish may very well die. Lionfish are pretty tuff, but they have a limit as to the abuse they can take.
Keep an eye out for local redness or red streaks emanating from the damaged areas, as this is generally a sign of a secondary bacterial infection.

 

[brenjada]

The sad thing is he was with a lion fish in the tank at the pet store and they were fine. That one was much smaller than ours. It makes me sad.

 

[saxman]

Fish at pet stores/LFS do not behave normally for multiple reasons.
They've generally just gotten in from the wholesaler where they've come out of a crowded holding tank, then are put into another new tank that's also likely too crowded which generally halts, or at least spreads out any aggression.
There generally aren't any territorial boundaries in LFS holding tanks...in fact, most are completely devoid of decor for ease of catching the fish when sold.
There also may be a "tank boss" in residence at the LFS that's keeping aggression down, but once that fish is no longer in the equation, another fish will step up and try for the number one slot.
In this case, a single question on a good forum like this one would have helped you make an informed decision, and shame on the LFS that sold you a triggerfish if you already have a lionfish (assuming they asked what you already had in your tank).
Just out of curiosity, what species of triggerfish was this?