Just to clarify things so that the poor lionfish species does not yet suffer once again from bad press, although the lion may have stung the trigger, and the trigger may have died from it, Lionfish do not "poison" anything. They do not have that ability. They are venemous, not poisonous. Venom is "injected" into the victim, via the spines in the case of the lionfish.
It is safe to put anything you want into that tank, that is suitable for the size.