Sounds like your fish have a bacterial infection.
Treat the pond with the Melafix as directed on the bottle.
Pimafix can be used in conjunction with Melafix.
See the link below for more information.
"Horton"

Here is a link that might be useful: Melafix and Pimafix.

Another alternative is to get yourself a box of "pond salt" and mix a concentration of 1 part salt 3 parts water in a separate bucket.

Dump the affected fish in the bucket for NO MORE than 10 minutes or until it looks like its having trouble moving around.

I've found that 2-3 minutes is about all I can watch. Then place the affected fish back in your pond. Should get better in a couple of days. Re-Salt in 5 days if no change is seen.

Then you can also add a small amount of salt to your pond. Instructions are on the box.

Please DO NOT use table salt. You will kill your fish with the iodine in the salt. I killed a fish this way early in my ponding career using table salt.

Thank you for your help. I really appreciate it. I will follow the directions on the bottles and I will also try the pond salt. That is if I can catch him.
Tes

Tes,
Do not waste your money on "pond salt". Solar salt for a water softener is far cheaper and the same thing. Salt isn't going to much for a bacteria infection but it can affect parasites that might be on the fish.
Mike

Thanks for the idea on the salt. I will check into the water softner. How much of it do I use?

same ratio 1 part salt 3(or 4) parts water. Just mix it around with your hand until disolved.

I don't have need for a 25# bag of salt. I don't mind paying a bit more for a 4#box that will last me for 1 year.

you can check the kh of the water.this stabilize the ph so it is a level value.if the ph swings it will stress out the fish.add baking soda to the pond,very slowly.it will bring the ph up to 8.3.do it slowly,you dont want to bring the ph up to fast.there is a bacteria called koi-zyme.it will stop the ulcers.