I have a Sohal he is about 8" long bought him at 4", he grew really fast for the first 6months then he has slowed down in the last year. I have him in a tank with a Sailfin and a Pacific Blue tang with no problem in a 240gal 8' long tank. I had him in a 120gal for awhile before I knew better, mine is mellow for a Sohal he isn't aggressive he just lets the Blue tang know whose boss every now and then by chasing him into the rocks but the Blue just comes out someplace else and acts like nothing happened. Its a good thing you will add him last since he killed a Naso I put in after him and the Naso was bigger, word of warning about the Tang Polizei here, you hopefully have a big tank 180gal+ Sohals are active swimmers and they are like the oceans crop-dusters they poop in mass quantities so a big skimmer might come in handy. If you have other Tangs in the tank Sohals hate other Acanthurus species Powder Blue, Achilles, and especially Clown tangs you might get away with Zebrasomas and Ctenocheatus tangs since mine leaves the Sailfin Tang alone. Hope this helps.
