Simply Koi and More Koi

I've just come home from work (1800 hrs) and found my 2 biggest kohaku dead, roughly 65cm, bought from Tosai, all koi bought from same dealer and no new additions since 2010.

All other 7 koi seem fine, swimming ok, no visible problems. There are no visible problems on the dead koi.

Does anyone have any suggestions at all as to what might have happened.

I'm at a loss and very upset/angry/pissed off
cheers
Carl

Carl,

If all the others are ok, this could be a coincidence but I don't like coincidences, I would much rather look for a cause so did any of the fish, especially the two that are dead, show any unusual signs at all?

What are your water test readings and have you scraped any fish?

Koi have never been scraped and water parameters haven't been checked for some time, i don't profess to be an expert, but I know when something would be wrong with them. They were perfectly ok yesterday tea time, all swimming and feeding ok, koi have never, ever flicked, flashed or showed any signs of irritation, etc...........I'm baffled
cheers
Carl

ps......... koi were all bought from a very reputable dealer 2 years ago, no other koi added since 2010, all koi in pond are from one dealer only.

Two koi dead. Largest ones. No prior signs of issues. Would tend the probabilities towards an O2 issue as the highest probability issue.

Tom,

That was my initial thought and the removal of two large oxygen users from the pond would allow more oxygen for the others so they would have survived but Carl said there was no unusual behaviour immediately prior to the deaths and I would have thought that all the fish gasping for air would have been an obvious sign.

But you've given me an idea.

Carl, is there any chance that the power went off for a while which interupted the aeration but restored before you noticed the dead fish?

I'm thinking this also and it maybe my fault.

About 10 days ago I switched air supply(supplementary) to pond onto a timer, it's on for 30 mins, then off for 30 mins during 0700 hrs-2200 hrs, then off completely from 2200 hrs to 0700am, when it goes back onto a timer.

The BD always has 40 lpm going through it even through winter, but the supplmentary air of 40 lpm was switched to timer in preparation for winter temps.

Other koi in pond are smaller but not by much TBH, circa 5 x 55-60cm koi, chagoi, kohaku(2), mukashi, showa then I have a shiro probably 50cm and another kohaku 40cm.......... all swimming feeding fine, been checking them all day and also just before I come to work tonight, worried as hell and cant wait to get home in morning

thanks guys
Carl

Manky Sanke wrote:Tom,

That was my initial thought and the removal of two large oxygen users from the pond would allow more oxygen for the others so they would have survived but Carl said there was no unusual behaviour immediately prior to the deaths and I would have thought that all the fish gasping for air would have been an obvious sign.But you've given me an idea.

I didn't have time to check them on the day in question as I was 12 hour days, but the previous night, about 1800 hrs, all seemed fine, it was only when I came home yesterday night, about 1815 hrs that they were dead, one floating, one sunk

Carl, is there any chance that the power went off for a while which interupted the aeration but restored before you noticed the dead fish?

I dont think so as, both of my sequence pumps are tempramental, and when switched off for water changes(every day), when they're switched back on, most times I have to give the impeller a flick to get it going, so a powercut would have been noticed

Carl,

I am sorry to hear of your losses mate.

Hi Guys, just an update as I've been busy with other things unfortunately

Cause of deaths were never found and all other koi are perfect and have been ever since the above named incident, just getting ready for winter now!!!

Grrrrrrrrr, roll on spring/summer
cheers
Carl

carlejo wrote:Hi Guys, just an update as I've been busy with other things unfortunately

Cause of deaths were never found and all other koi are perfect and have been ever since the above named incident, just getting ready for winter now!!!

Grrrrrrrrr, roll on spring/summer
cheers
Carl

Glad to hear that Carl, enjoy the winter my covers are on.