Dealing with the Sick Pond Fish

treating sick fish
prevent disease spreading by isolating the sick fish from the rest of the pond fish

Common problems

  • Fish that are normally vibrant in color but seem to be fading need more sunlight.
  • Fish that are gasping at the water’s surface means you need to add more aeration to the garden pond, or you may have too many fish for the size of the pond.


Keeping up with your pond maintenance and knowing what the fish require to keep them healthy is a big step towards prevention.

  • You don’t want to buy sick fish to begin with so make sure you purchase your stock from a reputable dealer. This is very important because you want to start off with a healthy group. You need to know the telltale signs of a potentially unhealthy fish. Otherwise you can end up contaminating your entire garden pond.

Having to deal with a sick fish is a concern, but there are a lot of treatments available for many of the diseases. The first step is determining what the disease is, the proper treatment and the cause.

There are several types of pond fish and each species has diseases that they are more susceptible to. Diagnosing a sick goldfish will be different to diagnosing sick Koi.

It’s much easier to identify a sick fish if you know its healthy characteristics first.

What are the symptoms of sick pond fish?

You’ll notice that your fish is acting out of character. Perhaps he’s not swimming properly or hiding, which is not the usual pattern. He may be swimming near the surface and appear as though he is gasping.

Then look for the physical signs. These will give your biggest clue as to what the actual disease or health problem is that you’re dealing with.

There can be many different symptoms which can be isolated ones or a combination.

  • Growths on the body of the fish
  • The body may appear swollen or the eyes are bulging
  • The color of the fish has faded and isn’t as vibrant as normal

Once you have properly identified the symptoms you have some valuable information as to what may be the cause.


Common problems that can make fish sick are

  • fungus infections
  • bacterial infection
  • flukes
  • poisoning
  • parasite infection
  • environmental
  • injury

Usually the fish that’s become ill will only be displaying one major symptom, and you’ll be able to determine the cause from this.

Bacterial infections often occur in a fish that has become injured. You may easily be able to see the wound, or there may be other symptoms like a swollen body and scales protrusion. Strong red veins might be appearing in the fins. These all could be signs of a bacterial infection but they could also be indicators of other diseases.

For example, the swollen body could also be a sign of dropsy. Or the red veins could also indicate a fish parasite infection or poisoning.

Course of action

The first thing you want to do is isolate the sick fish from the rest of the pond fish. Closely inspect the rest of the fish to make sure they are not developing any of the same symptoms or showing signs of not being well. You need to get all of the fish that are sick out of the pond as quickly as possible.

Make a list of all the symptoms. Look for experts advice on the treatments available.  This will help you with the best fish medication based on the symptoms.

Sometimes it will take a combination of fish medication and other measures to correct the problem. You may need to change the pond water to stop the spread of the fish disease.

In some cases you may not need any medication at all.