Instructions
Check for changes in swimming behavior. Check to see if your fish is swimming near the surface gulping for air, if he is lurking slowly on the bottom of the tank, if he is not eating or if his gill slits have turned from pink to purple. These are symptoms of a lack of oxygen in the water, according to petplace.com. Check your pump and the water's pH level.
Check for white spots, damaged fins or cotton-like growths. Chewed up fins could be a result of being attacked by another fish or of bacterial infection. Cotton-like growth or white spots is a symptom of ich, a disease caused by protozoan parasites. If you believe your fish has an infection, quarantine him in another tank away from healthy fish and consult the staff at a pet store as to which medication to use.
Check for swollen eyes. Swollen eyes are a symptom of the condition known as "dropsy." It may be the result of a bacterial infection or another underlying cause. Quarantine the fish and consult the staff at a pet store as to which medication to use.
Check for parasites. Look for any small worms or other creatures that have attached themselves to the body of the fish. Visible parasites can be removed using tweezers, says petplace.com.
How to Tell If a Fish Is Sick
Fish are often lower maintenance than many other kinds of pets. You don't need to take fish for a walk or show them affection. You don't have to worry about fish getting bored, and they are easy to ignore as long as you remember to feed them and clean their tank. However, if you want to keep your fish for a long time, you will need to be know whether your fish are healthy or not. The most important is to know when your fish are sick.