As far as Aiptasa...
This is a cut and paste from another web site....
Several species of butterfly fishes will eat Aiptasia. Unfortunately, they will also eat other corals, zooanthids, anemones and tube worms. We prefer to use the Raccoon Butterfly, Chaetodon lanula, or the Copperband Butterfly, Chelmon rostratus. Copperbands have a snout that allows them to get to more anemones; however, Raccoons will seldom bother reef inhabitants until all the Aiptasia are gone, making them the fish of choice for most applications.
Butterfly fishes less than 3.5" in length are seldom effective Aiptasia eaters. Once "trained", Raccoons will usually eat anemones off of rocks held in the tank with them. Raccoons used in our facility get used to being moved from tank to tank and will begin feeding immediately after a move. They're very effective!
Butterfly fishes have their limitations. Copperbands are most thorough; however, none of the species are capable of getting all the Aiptasia out of the cracks and crevices. More importantly, all of the Butterflies are likely sufferers of Post-Traumatic Shipping Disorder (PTSD). Only purchase these animals once they've been in a dealers tank for at least six weeks.
As far as the fish.....please research them each and decide more along the lines of if your system is appropriate for the long term survival and health of it.