Treatment can be handled in several ways depending on the severity of the infection.
1. If your Koi has a small sore you can dry off the wound with a paper towel and then treat the wound with hydrogen peroxide on a Q-tip. Let it soak for about 30 seconds before placing the koi back into the water. Repeat this procedure 3 days in a row. On larger sores after treating with hydrogen peroxide, again dry off the wound and apply Debride Medicated Ointment or Triple Antibiotic to the sore. Repeat this procedure 3 days in a row.

2. Potassium Permanganate (PP) mixed with water to make a light paste is a very effective treatment  instead of hydrogen peroxide. Do not use on a wound that is already healing because it will destroy the fragile new cells. Or if you need to treat the whole pond see Medications for instructions on using PP. Sometimes medicated food can be effective, especially if you have a hard time catching the fish or the fish are too small to inject. The problem with medicated food is that often times the fish that need the medication the most are too sick to eat it.

3. By far the most effective way to treat a bacterial infection is to inject the koi with antibiotics. This gets the proper amount of medication directly into the koi. But it is not without risks. Taking the Koi out of water several times can be very very stressful in itself, so use great caution with this approach. To do this guide the koi into a clear plastic bread bag, drain out the excess water, roll the koi over on its back, pull the excess bag back until the bag is tight around the koi and then inject the koi through the bag in the area between the anus and the ventral fins at a slight angle toward the head. Give an injection once a day for three days in a row and then every other day for two more injections. If the water is below 55 degrees spread out the injections to one every other day for a total of 5 injections, the koi's metabolism is very slow below 55 degrees. Use a 1cc diabetic syringe with a 25 gauge, ¾ inch needle. You will need to get the antibiotics through your local veterinarian. For photos illustrating injections click Here

Heat is very important in the healing process. During the summer months when the water is warm, bacterial infections grow very fast, but will also heal very fast fast once properly treated. During the winter time when the water is below 58 degrees wounds take a very long time to heal. If you have the ability to slowly warm up (5 degrees per day) the water the koi are in, to 76 degrees, it is impressive how quickly they can heal. Salt added to the water of koi with bacterial infections can be beneficial. If the infection has created a hole in the outer skin of the koi, water will begin to enter the koi through osmosis because the fluid in the koi is slightly salty. By raising the salt in the water to around .3% it will stop this process and spare the koi's kidneys the stress of trying to remove all this extra water. It is important to try and establish why the koi has a bacterial infection to begin with because unless the initial reason for the infection is corrected you will not be able to successfully treat the infection.