A very common word in the fish hobby is the term “dropsy.” What does this term mean?
Well, to start off, “dropsy” is NOT a disease. “Dropsy” describes a condition where a fish’s body balloons outward and their scales start to stick out, looking like a pinecone. This syndrome is caused by excess water in the body cavity or coelom. Excess water collects in the skin between the scales and around the internal organs causing the traditional “dropsy” appearance.
This presentation is merely a sign of poor kidney function. Freshwater fish live in an environment that is less dense than their bodies. Through passive diffusion, water is constantly trying to even out the fish’s density by pulling water into the body tissues, mainly the skin and gills. A freshwater fish’s kidney works very hard to remove excess water and pass it back out into the environment with other waste. If the kidneys are not functioning correctly, water is not removed effectively and the fish starts taking on water.
Many different disease processes can cause this syndrome, including stress from poor water quality, inadequate diet, tankmate aggression, tumors, parasites, viruses and bacteria. “Dropsy,” or more clinically edema, is simply a sign that there is something wrong affecting the kidneys and not a specific disease process.
When your fish takes on this appearance, don’t assume it will be corrected by dumping in antibiotics. Not only is this harmful to your fish, but it gives owners unnecessary exposure to the drugs as well. Not to mention that all OTC fish meds are not controlled or evaluated in ANY way. Start by checking your water parameters, evaluating your fish’s diet and making sure no on is picking on them. If you do not find a clear cause, contact your local fish veterinarian.