The symptoms of dropsy in fish is a distended or swollen body with protruding scales. Dropsy is also known as ascites. The affected fish may appear lethargic and may not eat.
Dropsy isn't a disease itself, but actually a symptom of another underlying disease in the fish.The reason the fish's body swells is due to a build up of fluid in its body cavity and internal organs. This may occur if the fish's kidneys are affected, for example. There can be many different causes of fish dropsy, and it is usually difficult to know exactly what the cause is.
However, one common cause of dropsy in fish is a bacterial infection byAeromonas. Aeromonas is normally present in all aquarium water, however, it sometimes causes illness in fish, especially fish that are stressed due to poor water quality from overcrowding or infrequent partial water changes. Also, some species of Aeromonas are more pathogenic than others. Infection byAeromonas will sometimes cause red streaks or sores on the fish's body (but not always).