That's a tough one. There is a chance it will work out, but it's a gamble long term. I've seen 3 different yellow tangs ho postal in a 90 gallon. I would pick one, and those truncated tangs are an underused favorite of mineThought I'd revive this thread. Thoughts on a squaretail bristletooth and a yellow tang together in a 90 gallon? The squaretail has been there for about a month and is sitting at just under 2 inches tip of snout to end of tail, so ~1.5 inches standard length. The yellow, if I do add it, would be about 3 inches standard length. I do have plans to upgrade, but that likely won't happen for at least 5 years, so for all intents and purposes let's pretend that the 90 would be their forever tank.