Pretty cool fish. Quite peaceful, as long as he can't eat other fish. They do get larger then most, a bit over a foot long, but almost as tall. Image a small pizza floating around in your tank. One or two should be fine in a 220 (is it an 8 foot?) for quite some time. Maybe eventually needing an upgrade. Probably the least active jack (good thing), and is a open water swimmer (will be out almost 100% of the time). Avoid keeping with overly aggressive tankmates that will pick on the Lookdown, like Clown Triggers or giant Hawkfish.