I hate to be the tang police, but I'm going to step in and do so. Tangs, particularly a Sohal or Regal, but really any tang, have no business being in a RSR 170 (34 gallon).I could see a tomini, if purchased *very* small and with a large addition of nori on a daily basis making it 1-2 years before outgrowing that tank. Mind you it will be cramped the entire time, and will likely be a bit on the stunted side at the end of those two years.A Sohal is often murderous in a 210 gallon tank (I've seen it), and that's when they are well behaved. They, and regals, and really most of the long body and larger tangs need to swim a ton. My desjardini is ~4 years old, has been bigger than my hand for a while, and was clearly cramped in my 5' 170 gallon display.I got a small naso (guessing 3 inches at most) at the end of October, in typical recently imported thin condition. He (or so I hope) is already an inch larger, and plump, I expect he'll put on another inch or two in the next year.On a more positive note, there are plenty of cool fish that fit in a nano. Many wrasses will do nicely (some are jumpers, consider a thin glass lid if your species is known for it). The common pair of clowns would do nicely, the really do have great personality.I'm not personally a fan of cardinals, but they do well in that space.If you're on top of feeding a coral beauty might do well (coral nipping risk, but a high success rate). Other dwarf angels are a solid maybe.Many gobies, blennies, pseudochromis, and hawkfish will do well.I would avoid dragonets no matter how badly you may want one. I would also avoid chromis and damsels for behavioral reasons.Royal gramma.
