It's a pinnatus batfish.
They look great when small, but really present quite a few problems with keeping them.
They are very, very passive fish and if not careful will get destroyed if housed with the wrong tankmates
one other main issue is they really only look good when juveniles. They grow into their fins until they are pretty much a fancy dinner plate.
This how they look as adults;
and they get absolutely huge like most batfish, so you need at least a 240 to keep them.