Question
Hi Robyn,

I have a 14" koi for 3 years. 3 weeks ago, I notice a corn-size bulging dark pink spot (not an open ulcer) on her body. I netted her and swabbed the spot with Betadine solution then place her on a quarantine tank with Melafix and Salt.
A week later, the bulge seemed to flatten and the dark pink turned pale. But it remained there even after treating it for 3 weeks. Should I let put her back to the main pond and let nature heals or should I apply other medication?

May I send a picture of her? I have a picture but can not find provision in this site for attachment.

Thank you for your time.

lee
lee

Answer
I am sending this same message to All Experts and the e-mail that you sent.

I'm sorry that your koi has the thing on her.  From the photo that you sent, it does look like an ulcer to me (more so than a physical injury).  Ulcers are usually caused by Pseudomonas or Aeromonas bacteria which are found in most ponds.  The MelaFix and salt may help some but she may benefit from antibiotics especially injectable ones if you can find a koi vet nearby.  The product KoiZyme works well to prevent ulcers but won't help once the koi has one.

It's really up to you if you want to put the koi back.  As far as contagions go, the other fish have already been exposed to the same thing (and may not have symptoms).  In quarantine, you can treat her with antibiotics and other medications for less cost.  At the same time, quarantine is stressful on her.  When fish are unhappy, they may not heal as readily.  Personally, I would put her in the main pond and treat that pond with salt and MelaFix as the other fish may also develop ulcers.  I would also add some KoiZyme.  Treating the entire pond with antibiotics is usually too cost prohibitive and could kill good bacteria too.  Ideally, the koi would get an injection of Baytril for the ulcer.

Good luck!