What causes Koi Ulcers, body sores and bacterial infections?

Bacterial infections such as Koi ulcers are open body sores on your koi. Koi ulcers are a secondary bacterial infection. The primary cause of koi ulcers is parasites.

Koi Ulcers and body sores can also be caused by poor water conditions, rough handling of your koi or your koi hitting themselves against sharp rocks or objects in your koi pond. Anything that damages the slime coat of your koi fish can cause ulcers.

The “slime coat” of a Koi acts like a suit of Armor. The “slime coat” protects your Koi from millions of harmful bacteria in your koi pond water like the deadly bacteria Aeromonas/Pseudomas from invading your koi fish’s body which can cause serious bacterial infections like koi ulcers and body sores.

Koi ulcers and body sores can appear on your koi fish anytime during the year, however, they are found frequently in the spring, when parasites take advantage of the koi fish’s weak immune system, which is at it lowest point at this time of the year. Plus, you have the problem of poor quality koi pond water because of lack of filtering, proper care and water changes over the winter months.

Most koi ulcers and body sores start out as just a raised scale that looks slightly pink or red. As they grow the koi ulcers become open infected wounds and will grow larger and deeper if not treated. Please remember, koi ulcers are caused by something else, they just don’t appear for no reason.

If you treat the koi ulcers and don’t treat or correct the problem that is causing the koi ulcers the ulcers will come back. So treating for parasites, correct handling of your koi fish, removing sharp stones from your koi pond and perfect pond water quality is a must in order to keep the ulcers from returning on your koi fish.

Aqua Meds offers three treatments that will help you cure koi body sores and ulcers: Aqua MedZyme, Ulcer Aid Rx and our medicated food like our Medi-Koi. Please click on each product for more details.

If you have a question or need help, I’m here,


You may also like

View all
Example blog post
Example blog post
Example blog post