Fish are fairly hardy overall, especially if they have the proper living conditions. However, sometimes, despite your best efforts, at least one of your fish will become ill, probably with one of the more common fish diseases.
If you have a sick fish, you will want to start by ruling out ICH, a fish disease that causes your fish to have white spots all over its body. These white spots look like grains of salt and are caused by Ichthyophthirius in freshwater tanks and by Cryptocaryon irritans in saltwater tanks.
These parasites attack the entire outside of a fish, including its eyes. Sometimes, ICH will also attack the inside of its mouth. The fish will exhibit behaviors such as rubbing against objects and may start gasping for air near the surface of the tank if the gills have been affected. The fish may also have a loss of appetite.
ICH does not go away on its own. To cure your fish of this disease, you will need to buy copper sulfur medication. To prevent your fish from obtaining an infection after the parasites are gone, you should also give it antibiotic medication.
Velvet is another fish disease caused by parasites. It resembles the symptoms of ICH but the white spots on the fish's body will look like dust and will be tinier. The spots might also appear gold or gray in color. Because of their small size, the spots may be difficult to see, so you will have to observe the fish carefully. You will notice that, as with ICH, the fish will rub against objects, show difficulty in breathing or gasp for air near the surface of the tank if the gills have been affected. Most veterinarians recommend using the same copper medication treatment used for ICH.
Your fish may also develop a fungal infection/disease. This will appears as a white or gray color on the body of the fish. The fungus usually appears on the fins or mouth of the fish. Sometimes this disease can be induced by injury from another fish in the tank. Some fish attack other fish with their fins, leaving wounds that are prone to fungal infections. You can purchase medication just for fungal from your local pet store or your favorite online pet supply retailer.
If your fish develops a bacterial infection, you will probably notice red or orange spots on its scales. One of the most common bacterial infections is called dropsy. If your fish is infected, it will appear bloated and its scales will stick out. This is usually a sign of internal infection and is often fatal. The fish will also appear lethargic and show a loss of appetite. There are several medications that are commonly used to cure bacterial infections, including tetracycline, penicillin and naladixic acid.
Of course, the best way to handle fish diseases is to keep them from occurring in the first place. Most fish diseases are caused by the environment around the fish. Is it a clean environment? Is the fish surrounded by other fish that are likely to attack it? Is it a stress-free environment? Is the tank big enough? Is the water quality ideal? Is the water dechlorinated? Take the necessary precautions to prevent your fish from obtaining any of the above diseases or worse.