TINY BLACK SPOTS ON TANGS ARE SAID TO BE COMMON.. IT MIGHT BE "FLATWORM" LIKE A PARASITE, THEY LOOK LIKE DARK SPOTS OVER FINS, GILLS AND BODY..FISH ACTS LISTLESS, PALE OR WHITISH AND SCRATCHES AGAINST OBJECTS...TREATMENT MIGHT BE A FRESH WATER DIP...YOU CAN IMMERSE FISH IN FRESH WATER FOR A SECOND, I READ FISH CAN SURVIVE OUTSIDE TANK FOR 2 MINUTES WITHOUT GETTING HARMED, MIGHT GET A LITTLE STRESSED THOUGH, ANOTHER ONE IS "TROCHLORFON"AND "PRAZIQUANTEL"IMMERSION MAY ALSO BE EFFECTIVE....BUY THIS BOOK, I READ ALL OF THE ABOVE FOR YOU(WHAT A NICE PERSON, I AM)IT'S CALLED "SETTING UP A SALTWATER AQUARIUM BY GREGORY SKOMAL....IT HELPS YOU WITH EVERYTHING AND TELLS YOU ON HOW TO FEED, LOOK FOR ILLNESSES, ETC. AND SOOOOO CHEAP THROUGH "HALF.COM" GOOD LUCK, IT'S WORTH THE INVESTMENT...BUY IT, I DID!!! GOOD ;LUCK, PATTIE