I maintained a Sohal Tang for nearly 10 years in a 500g. I acquired it as a 4" juvie and when it finally passed, it was just a hair over 14" long. For a Sohal, Attilla (his name), was relatively docile; only during feeding times did he tend to show his ornery side. He had to eat first, you see, then second, then third. But other than that, he was cool. He was gorgeous too and gave my family many hours of viewing pleasure. But you know what we gave him in return? An absolutely miserable life. Especially the last half of it. You see, a 500g 96x36x36" tank is far too small for a Sohal, imo. It was certainly too small for Attilla, who gradually went from swimming calmly with his tankmates to pacing somewhat restlessly to sometimes even dashing about in seeming fits of panic. He had literally outgrown all of his hiding places and had nowhere to go, nowhere to feel safe. He looked kind of silly in there too, kind of like a Mastiff in a dog run full of Beagles. For the final couple years of his life, I was semi-actively looking for a place to send him but who's gonna take a fish that's over a foot long, weighs a couple pounds, and packs a scalpel 24/7.
I'm begging you not to confine this proud and beautiful fish to a 180. Not even if he was the only fish in it. It will outgrow the tank in just a few years then possibly become aggressive, possibly become sick, and perhaps even succumb. Of course, it's pain will then be over. But speaking as someone who lived with this mistake for a decade, if you're a true fan of this fish, yours will last a heck of a lot longer.
