Fish become sick due to a variety of reasons. The reasons for fish becoming sick can be poor water quality, fungal and bacterial infections of the skin, disease of the internal organs such as tuberculosis, kidney failure,etc
Fish that are sick will exhibit a number of symptoms. Some of these symptoms are change in behaviour such as rubbing against rocks, unnatural swimming movements, loss of balance.
Other diseases such as parasite infestation can cause the parasites such as lice and worms to get attached to fish skin.
It is easy to identify the disease based on the symptoms. There are several online charts and tools which will help you narrow down on the disease based on the symptoms.
Sick fish need to be separated from the other healthy fish in the tank. This gives the sick fish a safe place to rest and recuperate. It also helps quarantine the sick fish and prevents the disease from spreading.
A hospital tank is a small tank in which sick fish can be kept. It is easy to provide medication to fish. The water in the tank should have the same temperature as that of the main tank.
Put in some plants in the hospital tank so that the fish gets some privacy and feels secure. Once the fish is completely cured, it can be reintroduced into the main tank.
The water, filter and other accessories should be thoroughly cleaned before reuse.
If there is a general infestation in the tank, medication can be administered directly into the tank. If activated carbon filters are used in the tank, they will have to be removed as the activated carbon can remove the medication from the water making the treatment ineffective.