The provocation of cysts on the fish's skin and inside it is what we know as the nodulosis, a disease produced by nodular parasites and fungi of a barely noticeable minute size.
La nodulosis has different sizes. In addition, there is a risk of spreading to the other fish in the aquarium. Its transmission is through its own ingestion since they can be added to the crustaceans that are part of their food. Since this type of cyst, inside, is composed of thousands of tiny spores that feed on the invaded host.
Small internal or external cysts
We can talk about a fish having nodulosis when we notice small cysts or lumps. They are usually very pale ocher in color and are usually on the fin, gills and fish skin. Although there are also times that they can be embedded within the body. If we notice that the fish is swollen, little less than a centimeter, is that you may suffer from nodulosis. At some stage of the disease they can suffer from the decomposition of the fins and the appearance of ulcers on the skin as well as mold.
It is not a certain science of the way in which the parasites are transmitted. But if it is proven that these microorganisms can live for a time without the presence of your host. It also does not affect all the inhabitants of the aquarium. Rather, it is typical of a group of each species.
Really if the nodulosis is internal and therefore difficult to detect, it is possible that the disease cannot be detected in the fish, unless the condition goes outside. However, there is no effective treatment to treat the disease.
It is recommended first disinfect the aquarium and separate sick fish from healthy ones so they don't get infected. The medicine to give them is the one advised by qualified personnel once the disease has been detected.