Growth on Koi

[Sarah Laupp]

One of my koi has two large, pink/red cauliflower-looking growths on him. One on the front of his face and one in the side on his gills. He’s had them for a long time but they have gotten really large this season. He still swims and eats like normal but I’m concerned these things are going to cause him problems if they continue to get larger. Any idea what it is and how we can get rid of them? We have 7 other koi in the pond that are healthy (no growths). We tried treating the water with Malafix when the growths were small but it didn’t do anything.

 

[j.w]

and welcome @Sarah Laupp
Not sure if this is koi pox or not as I don't have koi but I have some goldfish w/lumps on them and they are surviving for years. Mine have smoother looking lumps then these tho. Someone will help you here I am sure.

 

[Marck]

Perhaps it is a benign nerve sheath tumor.
Here is an interesting article about fish tumors.

Do Fish Get Cancer? - Fish Vet

Do fish get cancer? Unfortunately, yes, they do. Learn the signs that your fish may be in danger and what treatment options are available for cancer in fish.

cafishvet.com