Loss of fish

[wizzasmum]

At 800 gallons with two good sized koi plus goldfish, you were seriously overstocked. Basically a disaster waiting to happen. Any small thing could have pushed your pond over the edge quite honestly.

Oh now I feel really bad, as I had those fish for many years and always seemed healthy. How many would you suggest and presumably just goldfish?

 

[Lisak1]

Yes - goldfish are perfectly suited for that size pond. You could have several dozen in all kinds of colors!

The thing with koi is they continue to grow. They'll do fine for number of years - as you said "with no previous problems" - and then the point comes ("the tipping point") when they just overwhelm the system. And then - disaster.

 

[GBBUDD]

Maybe a dramatic pH shift

massive thunder storm says to me a ph crash along with the kh and gh.

 

[bagsmom]

Maybe it rained hard enough to allow run off to flood the pond? Fertilizers or pesticides washed in?

I wondered this also.

 

[miamicuse]

I had the same thing happened last year, natural pond with no feeding necessary started with 3 goldfish and everything worked fine for 3 years then the population grew to 30+ and in one day 32 dead gold fish only two smallest ones remain. I was debating between chemical runoff vs O2 level and I think O2 level, happened on a very hot day in August in south Florida in my 1000 gallon pond. To this day I have no idea what really happened but thinking O2 level was the reason.

 

[BenB]

Perhaps something - chemical washed into the water with that rain? Seems to have been a problem that originated with the rain event. Have you tried doing a third or more water change?

 

[GBBUDD]

could be just the rain itt's self and you had a ph crash