A very common syndrome in fish is dropsy. Once the signs have been recognized, the cause should be identified and an attempt to resolve it.

Dropsy is not a disease in itself. This term describes a syndrome that is characterized by the accumulation of fluid within the coelomic cavity of fish. As fish do not have a diaphragm, they have neither thorax nor abdomen. The cavity that contains all the organs (heart, lungs, liver, digestive tract, etc.) is called the coelomic cavity. Sometimes, for various reasons, fluid accumulates and surrounds the organs in this cavity. If it is present in small amounts, it may go unnoticed. If the volume of liquid increases, the belly of the fish may at first appear rounded and then, little by little, all the fish appear as swollen.

One of the major causes of dropsy is sepsis, which is the spread of a germ in the bloodstream. This occurs following a primary infection. This can affect the digestive system, for example, but also the reproductive system, the swim bladder, the kidneys, the lungs, etc. Virtually any untreated infection can eventually spread and spread throughout the body. Inflammatory fluid can then build up in the coelomic cavity.

The result of a metabolic disorder

In addition, the accumulation of fluid around organs can signal organ dysfunction. For example, heart failure, as in all animals, can lead to overpressure in the blood vessels. This excess pressure is managed by the body by the leakage of fluid through the wall of the vessels. This fluid can then end up in the coelomic cavity.

Liver failure can also manifest as dropsy. The liver is responsible for the production of many molecules but also for the elimination of multiple wastes. If it no longer works properly, the composition of the blood changes and this creates an imbalance between the blood and the surrounding tissues. Again, fluids can filter through the walls of the vessels.

Finally, many metabolic disorders can lead to dropsy such as kidney failure, for example. These disorders can be the result of genetic abnormalities, infections with bacteria, viruses, fungi or parasites. They can also be linked to degenerative organ dysfunction, especially in older fish, or tumors.

Dropsy is therefore not a very specific sign. Many diseases can manifest as a swollen appearance of the fish, with a distended belly. In order to guide the diagnosis, several elements can help the veterinarian.

The first and most important aspect is the age of the fish and its way of life. Does he live alone or with congeners? Has a new fish been introduced to the workforce recently? Does it live in an outdoor pond or in an aquarium?

Before consulting, carefully examine the other fish for possible similar signs (a slightly rounded belly) or different. Indeed, if the same fish or others have presented, in the previous days or weeks, other anomalies, this can guide the nature of the attack.

More specific signs have thus been observed:

• abnormal swimming;
• respiratory problems with a fish searching for air on the surface;
• abnormal coloring of the gills;
• etc.

Fish are also very sensitive to their skin. Thus, inspect them from a distance to identify any areas with an abnormal color, damaged scales or even more or less deep wounds.

If you observe a swollen belly in your fish, it is a sign of a condition, the nature of which remains to be determined. As explained earlier, this can be due to infection and therefore be contagious to other fish. If possible, affected fish can be isolated to avoid contaminating the rest of the workforce. A consultation with a specialist veterinarian should be organized. Some vets specialize in New Pets (NACs), others even treat fish only. Teleconsultation services are also developing for geographic areas where few specialists are accessible.

In conclusion, dropsy is an accumulation of fluid in the coelomic cavity and manifests as a swollen appearance or a distended belly. The causes are diverse but can be serious. It is therefore advisable to consult a veterinarian as soon as possible, having previously examined the other fish in the workforce.