I am wondering does anyone know of Goldfish as a pet? My situation is this. My wife and I had 2 goldfish since 1 1/2 ago from a Carnival. My wife just recently got two other fish from a neighbor and we waited for several hours to put them in the fish tank we have. Last week one of them "died" and the other one had some black stuff on the head, dorsal fin and the back fins and then some how whatever the smaller fish from my neighbor gave whatever black thing to my wifes fish named Edy and Evy. Does anyone know if that maybe a fish disease or some fungus? My wife bought some medicine called Maroxy. Any help would be greatly appreciated and thanks for the help.