koi sickness

Question
Thanks to dave for referring me to you... I have 2 1 foot long, 25 year old koi in a 55 gallon aquarium. Recently one of the has been acting sick. He sits on the bottom of the aquarium with gills pumping, then occasionally tries to make it to the surface to mouth breath. He has never had to mouth breath before due to plenty of O2. When he swims, it is as if his tail and rear section are not moving normally and will come back from the surface somtimes on his back, struggling to turn over. He also seems to have some trouble with his swim bladder. He is now eating very small amounts. The other koi is doing fine and seems concerned for her friend. The ph,akalinity,nitrites,temp are all in spec. Water had a 20% change recently. Any help in this matter would be greatly appreciated. Thanks - Boz

Answer
Hi Boz,
Wow, a 25 year old Koi? That's amazing. If the water tests out good in terms of ZERO ammonia and nitrites and very low nitrates (20 or less)
The best you can do is an extra water change or two and wait and see.

I generally don't like to immediately diagnose a condition and advise a medication that may not be necessary. Otherwise, I would think that the Koi is just experiencing old age problems. He is probably slowing down.

Please don't be shocked if you loose him. He has had such a long life for a fish that it shouldn't make you feel so bad to loose him. I know he must be dear to you and you have taken great care of him in order to keep him for 25 years. That's quite an accomplishment worth praise.

My best wishes to you and your Koi!
Karen~