Yeah, that's USD - it's a listing on LiveAquaria's Diver's Den.
And really, it's a matter of supply and demand. Demand for yellow tangs is pretty constant, so any disruption in supply causes an increase in price. And hey, two major things that impact supply just recently happened:
1) The ornamental aquatics trade is under severe attack in Hawaii, where this particular fish originated. Hawaii isn't the sole source of yellow tangs, but until recently it was a major player in the industry. With the ongoing difficulties in Hawaii, fish sourced from there, especially endemic fish like Potter's angels and golden dwarf morays, have skyrocketed in price. A few years ago, you could get a golden dwarf for $150 or so. These days, expect to pay $600 for one.
2) This little virus sprang up and caused a minor disruption in the economy. Maybe you've heard of it, COVID-19?
All fish are more expensive now. I bought a tomini tang in 2019 for about $50. These days I regularly see them between $90-$150. I've seen non-Hawaiian yellow tangs for closer to their original prices, but even there, expect to pay on par with the tomini.
But in this case - it's a Diver's Den fish, which in LA's estimates adds a bit to the price. It's a Hawaiian fish, which adds to the price. And you're paying the COVID-19 markup. So there you have it.