Backyard Aquaponics
A place to discuss aquaponics

The systems are separated from each other.

Big changes kill fish.. A change in pH from under 6 to 7.4 is enormous.
It may not sound like much but keep in mind that pH is a logarithmic scale meaning that a pH of 6 is 10 times more acidic than 7. If for example your pH was at 5.4 and you changed it to 7.4, you've changed it by a factor of 100, 7.4 is 100 times more alkaline than 5.4.

The change from 6 to 7.4 was over a few weeks.

Now there is another koi swimming up-side-down, but till breathing.

This is the previous koi which died.

I havnt had much luck with koi either, I heard they were hardy and resilient. They're all gone to fishy heaven in the worm farm now, no idea what killed them and the goldies with them in the tank after 1 1/2 yrs. I have silvers in another tank in the same system that are fine and, touch wood, healthy.
I can sympathise with you even though mine weren't anywhere near the size of yours.

Oh that is sad, I'm so sorry. I understand that it is possible to have a biologist do tests to learn what killed them. Jenny from Solid Gold Aquatics had fish deaths last year and documented the story here:


Of course you want to know what happened, but it may not be feasible.
If like in the case for her fish, it was determined to be a pathogen all of the fish tanks needed to be sterilized. You may have worried about this already and I'm sorry to be the one too bring it up. It can be a toss up between what is worse, not knowing or knowing what killed them. Best of luck to you and your beautiful fish.
Brian

Had our first harvest trout from the system last Sunday.
The temperature in Perth was 37 on Friday and the water temperature was above 24.
So we decided that it was enough.
A good decision as 2 of the trout did suffer from the heat and didn't survive.
Well, really no trout survived, but that was due to the iki jima and the knife. :-)
A total of 16 trout was harvested/gutted and 14 were vacuum sealed and put in the freezer.
We left 2 for our first smoke on Sunday.
And I must say, it was delicious. My first time of smoking on the Weber turned our great.