North Wales Koi Club Forum

hi,
I have lost 5 largish koi over the last few day. I have done an ammonia and nitrie test and ph test.the nitrite and ammonia were normal but the ph was 8.4 is this far too high? how to I lower the pH?any suggestions helpful
thanks in advance
Hadyn

Hi Hadyn,
do you have any other info - any behaviours noted, signs of distress, marks on the fish, heavy mucus, did you do a scrape to check for parasites etc.
Also taking the weather into account what air do you have going into the pond, how many gals is the pond.
How old are the fish? are they long standing residents? have you introduced any new fish?
richard

Hi,
the fish are rubbing and have done a scrape but only found 1 fluke.
Air is fine we have a big waterfall and a large surface area
The pond is roughly 35,000 gallons
All the fish are new to the pond ranging in age from Jaws (40 years old 32 inches) to tiddlers

we took a sample of water to the local garden centre and they tested pH (we hadnt bought that kit yet) and it was 9.0 so we are replacing a lot of the water, we believe its due to lime seeming in from the cement on the one edge with slabs

yes 9 is high but I would not think it would be the killer as it is not selective so all fish would be equally effected, but i could be wrong - i would get some scrapes though just to eliminate the possibilities of parasites

Hi Hadyn,

Sorry to hear you are having problems. I seem to remember that you said that your pond 35000 gallon pond had no filter.

If the ammonia and Nitrite levels are OK (zero?) then I wouldn't have thought your pH level is the root cause of your problem. What pH is your tap water?
Another cause of high pH could be algae, have you got green water? With green water you can get a big daily fluctuation in pH.

There are products on the market to lower the pH, I've also heard of vinegar being used. I don't know if you aerate the pond but plenty of aeration will also help.

With the symptoms you describe I would be inclined to think that parasites of some sort or other are the cause. I would take scrapes from a few fish again and check them first under 100X magnification and if you don't spot anything increase the magnification to 400X.

It's very difficult to give specific advice from afar, is there a koi club in your area where you could get some assistance from fellow koi keepers,

Colin

Hi Hadyn,
But don't dismiss the possibilty of parasites, I would still go down the road of more scrapes. Could be a lot smaller than Flukes, Chilo or Costia.

pH would be unlikely to be selective, seeing that you have only lost larger Koi, I would say especially with warm weather, lack of Oxygen could be the cause tends to get the bigger Koi first.
Try to get some more air in the pond, difficult with the size, but a couple of large submersible pumps with the returns pointing in the air.


regards
Dave.