The main goal for getting a bigger tank is to have more space for fish. I recently lost my 5 year old Achilles tang for reasons as unclear; otherwise all fish remain. Have a bunch in various QT tanks already, from varied sources. Regal and rock beauty Angels and black tang from local reefers. Two fairy wrasses, a quartet of femal bimacs, and a zebra eel. Another local guy has a small spotted unicorn tang that I'll prob take. Even a 450/400 will eventually be too small, but it's better than where the fish is now.