- Have you tested your water?
- No
- If I did not test my water...
- ...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.
- Do you do water changes?
- Yes
- What percentage of water do you change?
- 31-40%
- How frequently do you change your water?
- Every month
- If I do not change my water...
- ...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.
Hi All - New to this forum as we are new owners of Koi fish that someone donated. Newbie owners so please be kind 
Hoping that your experience and knowledge will help us!
Two of the Koi have these lumps - see pics! Another Koi seems to be developing something similar as it has a round discolored mark on its skin. (ignore the white spots in the first pic as that is just tiny bubbles captured..nothing on the fish) I assume the lump would develop after some time. The fish are in a tank with a heater set at around 80 degrees F. We currently have these Koi in separate tank from Koi that seem healthy. P.S. They were all together in same tank with previous owner. The fish do not seem lethargic or in any way unhealthy except for the skin appearance. Though the one with discoloration is hanging by the heater constantly!
Any thoughts on what it is and if it is treatable? Is it any bacteria that can be contagious to humans? Thank you for your help in advance.
Hoping that your experience and knowledge will help us!Two of the Koi have these lumps - see pics! Another Koi seems to be developing something similar as it has a round discolored mark on its skin. (ignore the white spots in the first pic as that is just tiny bubbles captured..nothing on the fish) I assume the lump would develop after some time. The fish are in a tank with a heater set at around 80 degrees F. We currently have these Koi in separate tank from Koi that seem healthy. P.S. They were all together in same tank with previous owner. The fish do not seem lethargic or in any way unhealthy except for the skin appearance. Though the one with discoloration is hanging by the heater constantly!
Any thoughts on what it is and if it is treatable? Is it any bacteria that can be contagious to humans? Thank you for your help in advance.
