Some of the signs and symptoms used to diagnose disease in fish include inactivity, frayed fins, loss of color, erratic swimming and difficulty breathing, states FishNet. Other indications of disease can be open sores, bulging eyes and rapid breathing.
There are many signs from infection in fish that indicate a poor health condition or disease, notes FishNet. The three types of infection common to fish are bacterial, fungal and parasitical. Bacterial infections have a range of symptoms from inactivity, loss of color, bulging eyes and difficulty breathing. A bloated body, cloudy eyes, open sores and reddening of the skin can all be symptoms of a bacterial infection.
Fungal infections are indicated by darting, erratic swimming, scratching and visible cotton like tufts on skin, eyes or mouth, explains FishNet. They are often a secondary result of another type of illness.
Infections from parasites are displayed by inactivity, loss of appetite and visible spots or worms. Excess mucus, film on the body and scratching are also signs of disease. Diseases in fish vary depending upon what type of water and conditions surround the fish, according to FishChannel. Whether the fish are tropical, freshwater or in an aquarium, different environments cause different signs and symptoms of disease in fish.