Question
I live in Florida and it has been very hot in the high 90's. Yesterday I had a koi at the top of the water gasping for air.  I put some fresh water in the pond and added two small air aerators and he seems to some out of it.  but today I had a different koi start swimming and jerking in circles and tried to beach himself on some rocks.  I took the fish out and put in a smaller tank and put the air aerators in with it but it didn't help he died. The fish looked very healthy over 5 lbs and no signs of any injury.  I just don't know what happened.My pond is about 2500 gals and have only now nine koi. does anyone know what could have been the cause?

Answer
Hello Donna! So sorry to hear about your Koi! It is a bit difficult to diagnose the problem at a distance, but I can tell you what I would be looking at:

a) Immediately test ammonia and nitrite levels in the pond. Do 1/3 water changes daily and stop feeding until levels return to zero if they are anything but zero. In addition check the pH and add air stones.

b) Keep a couple of large air stones going at all times. Large Koi need a lot of oxygen and warm water is notoriously low on that commodity.

c) Always, always, always de-chlorinate any tap water that is put into the pond. Although small quantities of chlorinated water can be survived by the fish for a certain period..the chlorine damages their gills and over time the amount of oxygen they can take in is greatly reduced.

Hope that helps!

Brigitte
www.pondmarket.com