Ocean Surgeonfish GALLERYAcanthurus tractus
If you will notice, some of the fish have black or gray spots on their bodies or fins. Commonly known as Black Ick, Black Spot or Tang disease, it is actually an infestation of tiny Paravortex turbellarian flatworm. Many kinds of fish get Black Ick, but the Surgeon fishes seem exceptionally vulnerable. Of course, the fish's light color makes it easy to see. I have also seen Bar Jacks with black spots on their bodies also.