I am a new member. I have a small garden hobby pond with about 200 gallons in it. I keep comets mostly and the occasional koi fish. The pond is about 7 years old now and I enjoy it very much.

I have a question for the experienced folk out there. One of my comets, 5-6" and about 5 years old has something about the size of a walnut coming out of her distended and yellowed back end, vent, whatever it is. It appears to be transparent and it looks like she's trying to poop it out. I don't know what this is or if she's going to die. She appears to be behaving normally but she wouldn't eat just now and this thing wasn't there two days earlier. The rest of the fish seem to be fine. Has anyone had experience with this type of problem before??

Hi Sunflower. I've been coming here for quite a while but I totally forgot about the forums. I've been in the hobby for 28 years and we used to have 14 ponds and we imported, bred and raised high quality Koi and Orandas. Let me ask you a few questions about your sick fish.

What size is your pond?
How many fish are in it?
Do you have a bio-filter?
If so, what size is it?
Do you make water changes from the bottom of the pond?
How often do you feed?

I'm from Canada where winter is almost upon us. Are you from a warmer climate?

It is possible that your fish has an internal bacterial infection or it could be a tumor. It's really difficult to tell. If water conditions become poor, the immune systems of fish can become weak and they are unable to fight any infection that may come there way.
Try making a one third water change from the bottom of your pond and replacing it with fresh water, using a conditioner to remove chlorine and chloramines from the water. Let me know if your fish seems to be doing any better.
There are medications on the market that might heal your fish but that will depend on how far along the infection or tumor is.

Yours Koily, Lorraine

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