This disease is usually introduced to an aquarium through an infected fish, live plants, live coral, poorly cleaned live food, and pond water. Gill Flukes and Skin Flukes are common parasites of aquarium fishes. Both are transmitted from one fish to another. Fish will shimmy and be seen scratching themselves against aquarium fixtures. Flukes cannot be seen with the naked eye, but may be seen with a strong magnifying glass.
Fish seems to be sprinkled by little white spots on the fins and body.
Infected fishes may live many months. Fish begins to shimmy, and you can see a faint, whitish abnormal cast to their scales. The cause is a small leech that clings to the fish's scales and gills. This parasite reproduces quite rapidly, and will kill a fish very quickly. Leeches are introduced to an aquarium if pond water is added to the tank.