Koi Carp Problems

[skippyfi]

Hi all!
We have a large pond, contiang just over 2000 gallons. We have a mix of Koi and Goldfish and everything has been fine, up until about 2 weeks ago! One by one we have had Koi dying. None of the goldfish have died, just Koi. Some of them have had a furry type mould on them, but not all, (We have bought from our local Koi specialist the correct medication to put i nthe water) Most of then have not had a mark on them atall. We have performed the necessary water tests and all the levels are fine.
Really dont know what to do as It breaks my heart every time i go down to the pond to find a new casualty.
Would really appreciate some advice.
Thanks

Fi

[blackietwo]

The answer is usually in the water, but you say you have tested it! did you test it yourself? or did you take it to be tested? some of them you can buy are not that accurate. It is heart breaking to lose them when your trying your best to rectify it. If your advised medication as not worked maybe its something else. Its costly to lose koi as they are so expensive depending on size and colours as you know. It may be worth you taking one to a vet type place that deals with fish also, expensive maybe, but long term not as costly as losing them.There are so many things that can kill koi as they are so vulnerabe to all sorts. Do you filter by bio, or ultra violet? I would recommend ultra for koi.

[hammerman]

Are you putting air into the water in any way...waterfall, fountain, air pump ??? It is very humid and i've lost several massive golden orfe at work and all the fish are gasping for air....especially first thing in the morning.

My koi at home get serious air pumped into the pond and they are as happy as Larry.

Might be worth a thought.

[skippyfi]

Thankyou both for the advice!
blackietwo - We have a 'Tetrapond' kit which we test the water ourselves with. I tested again last night and all appeared fine.
It is really frustrating as we have recently re stocked the pond after an accident where the filter leaked and the entire thing emptied!!!! I think perhaps we should just stick to land pets - far more straightforward!
Thanks

[skippyfi]

hammerman - We have a waterfall, 2 large air pumps in the bottom of the pond and also a couple or air balls dotted around. I was worried that perhaps we were over - aerating it!??
I have said to my other half that the water doesnt feel as cold as ti has previously and wondered if this could be the cause, but how do you keep 2000 gallons of water reasonably cool?
Thanks for the advice

Fi

[skippyfi]

blackietwo -
Ooh forgot to say, We have ultra violet light in the actual filter. Would you reccommend we also have a separate ultra violet light??
Fi :)