Bad water quality in the aquarium is the main cause of Dropsy which is a bacterial infection of the fish. One of the symptoms of this condition is the huge swelling of the body of the fish. This is due to the fact that the fish absorbs more water than it can dispose off. There are chances you might mistake this big fat belly condition as to something like pregnancy. So whenever you see the big belly in your fish chances are that it might be pregnant and there are also chances for the fish to get infected with dropsy. The sides and the stomach of the fish would bulge out. With such bulging it appears at thought the scales of the fish will come out. The scales look as if they are going to come out. Moreover the eyes of the fish might also pop out.
Sometimes this condition is contagious so it is better to isolate the fish that is affected. There are also chances that the fish might recover from this condition without any treatment too. Fish TB is also possible, which is one of the internal infections caused in the fishes. Before treating the fish see whether the water is of good quality. If it is quite good then you can go for treatments with antibiotics. Do check the water for high nitrate content. It is difficult to find the actual cause of this disease. One of the causes of the infection might be damage to the kidney. Kidney damage might be due to over treatment with drugs. This might give a '''pine cone''' appearance where the scales look projected.
Early detection of dropsy can help you prevent casualties. When the fish is infected by this it will not feed properly and it will be off-color. You can notice sunken eyes in the fish. Either the fish will hang on the top of the aquarium or it might stay in the bottom of the aquarium when it is suffers from Dropsy. Internal bacterial infections are not that easy to cure. However there are medications like Penicillin, naladixic acid and tetracycline can be used for the treatment.
Fish varieties like gold fish, guppies, gouramies, betta, and cyprinids are those that are affected by dropsy in poor water conditions. Since we know that the poor water condition is the main reason for this infection it is the duty of the owners to makes sure that it is set right first. From the varieties of fishes available the gold fish is the one that is mostly affected by dropsy. The presence of high nitrates in water is one of the main reasons for dropsy. So take care that the water is clean to prevent dropsy.