Actually, the rarest fish is the Clownfish. Not just any clown fish, a black and white Clownfish with an orange face. My LFS
had some come in on some live rock one time. The owner said that you cannot hardly find these in the ocean anymore. (Or quite possibly, at all. I don't quite remember. Story still applies.) He says that local colleges have offered him big money for the tank they are in (If I remember correctly around 4000 for the whole shebang.) He still won't sell it.
It is kinda sad, because the colleges could be trying to help this poor species out.
I do apologize if I am misinformed about these beautiful fish. (I hope that I am not.