PlanetCatfish.com

...maybe these folks:
http://reuters.excite.com/article/20050 ... SH-DC.html

There was an article in the New York Times Sunday Magazine a while back on the "up and coming profession" of specialized vet care for fish. I guess they're in the US. The article focused on pond fish such as Koi and Goldfish. I have never met a fish vet.