fish in new build pond dying

[fabioburke]

I've got a new build 11ft radius, round 4,000 litre pond.
With a bioforce pressure filter with U.V plus another U.V.
The first fish that went in were a Koi carp and goldfish that I've had from fry and lived in a tank indoors for a few years.These have survived and seem content in the pond for nearly 2 month but 3 fish I've introduced at intervals since then have all died within 3 weeks.Certainly the first was mauled(a ghost carp) but the others showed no obvious signs and the most recent was a slightly larger Koi.I've had carp ponds before elsewhere and never encountered this.Please can anyine advise me?

[redcrx]

according to my other half its one of two thing
firsly test your water. The old stock has acclimatised to the water conditions you have but the new stock is getting a shock and dying off.

Possibly your present stock is KHV infected but immune and the ne stock is being infected.

he suspects the first one though.

[fabioburke]

thanks redcrx,am testing the water tomorrow-will let you know how I got on.

[redcrx]

good luck!
we have our koi in a tank inside at moment, just waiting for a pond to be built! But Mr CRX has had koi for years and has some monsters in ponds at his mums and sisters.