IMHO, a 30 gal is fine for a warty, but IME, anglers are really best kept in species setups. As mentioned, you really don't want any browsing fish such as angels, tangs, triggers, etc as they will indeed pick at the angler.
An angler will try to eat anything up to twice its size, and large meals for anglers often = death because the food will begin to decay in the fish's GI tract before it is digested due to the angler's very slow metabolism.
You'll also want to try and keep the angler in the water as they can swallow air and will require burping if this happens.
JME/JMHO