I think this is actually a spotted scorpionfish, Scorpaena plumieri, but I cant say for sure without a little more information about this individual fish's origins. Scorpionfish are very variable in color and pattern, and there are probably several dozen species throughout the world's shallow subtropical seas that look very similar to this.
If you know anything about this fish's geographical origins, it'd help narrow it down a lot. But I'm confident that it's a scorpionfish and not a stonefish.