You want a 'large fish' for the 90. This is a bit of an oxymoron. Truly large fish should not be in a 90. This tank is not suitable for Tangs, large Angelfishes, Puffers, Groupers, Triggerfishes, and others that get large.
Although the 90 could house a large Puffer, Grouper, or Triggerfish for a while, it will outgrow it fairly quickly.
If these are the kinds of fishes you want to keep then you should consider a larger display tank and system.
Your 90 is best suited for dwarf Angelfishes, small Wrasses, some Gobies (depending upon the type and your tank features), some of the 'thin' Butterflyfishes, Damsels (including the Anemonefishes), 'dwarf' Puffers, etc.
If you're looking for a nice 'center piece' fish for the 90, consider some of the very loudly colored, delicately marked, small wrasses. You already have a pair of Anemonefishes, so in essence, you have already put in your 'center piece' fish (pair).