Koi are dying, any advice please.


Joined
Jan 3, 2018
Messages
4
Reaction score
2
Country
Hi All,
I have just joined as I read up a lot of information on your site. I have a 6500 litre pond, bottom drain into an Oase filter with koi, goldfish and a sturgeon. I have been devastated with the loss of 8 koi on the last week and still struggling. I have posted on another site for help but we can't seem to work out what the issue is.
The koi were found floating on the pond and a goldfish was found lying flat on the bottom of the pond. 3 Koi were still alive and we put these int the QT. I checked water parameters (amonia 0, Nitrites 0, PH 7, KH 300) I have done a number of scrapes, checked the gills and have come up with nothing. The 3 koi did not make it. In desperation I bought the goldfish indoors and increased the water temperature slightly with a little salt and this fish has recovered but still living indoors now in a small QT. My pond is not heated. Another 2 goldfish were also starting to swim on the surface and I popped them into the outdoor QT with salt and they too have recovered and are back in the pond.
I am struggling with my other koi as another 2 are not doing great and I don't know if they are going to make it either. One is almost floating on the surface and the other looks distressed swimming erratically and coming up for gulps of air. all I can think and all the reading up I have done is this might be something to do with the swim bladder. I have put these 2 into the outdoor QT with salt. My only reason for using salt was a last resource as the pond temperature is only 4 degrees and before Christmas this dropped down to 1 -2 degrees. Te pond does have the air stone on the bottom drain but with a smaller air pump for the winter.
My sturgeon has also stopped eating but is still moving around.
I have tried to give as much detail as possible with the hope that maybe someone may have an idea as to what the issue could be. Any help would be greatly appreciated, Thank you in advance.
 
Joined
Sep 14, 2013
Messages
4,064
Reaction score
3,171
Location
Cincinnati, Ohio
Hardiness Zone
6 A
Country
Fome, Welcome to our site, I'm sorry for the circumstances.

I don't think this is a swim bladder issue, as it wouldn't affect most of the fish simultaneously. How long have you had these fish, any new additions? How big were the koi you lost? Are the two remaining koi still in the pond? What is your water temperature?

Is it possible something got into your pond?
 
Joined
Oct 28, 2013
Messages
7,128
Reaction score
8,016
Location
Northern IL
Wow! I am sorry that your first post is so dire!

I am wondering the same as @Tula - if something got into the pond, perhaps of a chemical nature? Or could it be that your pond is too small for so many koi? You don't say exactly how many there are, but you lost 8, then 3 more, then 2 that are struggling... plus a sturgeon, plus goldfish. That's a lot of fish in 1700 US gallons. Is it possible the balance was just tipped too far with so many fish?

I don't know water parameters well enough to help with that - maybe @MitchM will chime in here.
 
Joined
Jan 3, 2018
Messages
4
Reaction score
2
Country
Wow! I am sorry that your first post is so dire!

I am wondering the same as @Tula - if something got into the pond, perhaps of a chemical nature? Or could it be that your pond is too small for so many koi? You don't say exactly how many there are, but you lost 8, then 3 more, then 2 that are struggling... plus a sturgeon, plus goldfish. That's a lot of fish in 1700 US gallons. Is it possible the balance was just tipped too far with so many fish?

I don't know water parameters well enough to help with that - maybe @MitchM will chime in here.
 
Joined
Jun 11, 2012
Messages
6,960
Reaction score
7,060
Location
Water Valley, Alberta
Hardiness Zone
2a
Country
At those temperatures, your pond is close to forming ice on top, has that happened?
It would be helpful to know more about your pond plus total fish population/sizes.
Did you change circulation or filtration setup for winter? How long since you made the change?
A picture usually helps.
 
Joined
Jan 3, 2018
Messages
4
Reaction score
2
Country
We have had no ice as we have air movement from the bottom drain. We have not changed anything on our system except to use a lower air pump for the winter and a lower pump to cycle but we had a radical drop in temperature before Xmas to -9 and then back up to 10 degrees over a short period of time.
I have 4 goldfish (2-3inches), 12 koi (8 deceased (4 were between 12-15 inches) and 4 alive (between 7 and 12 inches)) Pond was covered with corrugated polycarbonate sheets with gaps for gas releases.
Since my last post, we have done a 30% water change and I have been adding some clay for the fish. I have not lost any further except for one who we now have indoors in a very slow warming QT as he cannot swim under only float and on his side and keeps lodging himself under the air stone pipe to keep upright. I don't know his outcome. The other fish look to be a little better today and are all at the bottom of the pond and look to be doing the norm but I ma keeping a close eye on them. I will try and get a picture for you over the weekend. Thanks.
 
Joined
Jun 11, 2012
Messages
6,960
Reaction score
7,060
Location
Water Valley, Alberta
Hardiness Zone
2a
Country
I'm interested to see how you have the cover arranged.
If your pond water temperature dropped down to 1-2 Celsius, you may have had an ice cover, not realized it and the larger fish perished first. You have a lot of fish for the pond size.
If some chemical did get into the pond, you could have a few cups of activated carbon in the filter system to help clear that up.
Your KH is fairly high (almost triple normal values), do you add anything to the pond? Do you have a GH reading?
 
Joined
Jun 11, 2012
Messages
6,960
Reaction score
7,060
Location
Water Valley, Alberta
Hardiness Zone
2a
Country
If you get a chance to read this again before the weekend, I would increase your aeration activity in the pond.
Given your high KH and neutral PH, I am leaning toward your pond having a too high CO2 level.
Using the calculator and paper below, your PH should be much higher than 7.0, given the high KH reading and low water temperature.
CO2 levels are dangerous above 20 ppm and your pond has been over 100 ppm.
https://pentairaes.com/co2-calculator
http://www.aces.edu/dept/fisheries/aquaculture/pdf/468fs.pdf
 
  • Like
Reactions: cas
Joined
Jan 3, 2018
Messages
4
Reaction score
2
Country
I lost another fish on the weekend and we were advised to empty the pond . We emptied the pond cleaned it and have refilled and restarted the filter system. This was 5 days ago now. I have not lost any further fish and they are doing what we would expect now, on the bottom of the pond. I am monitoring ammonia due to a new start and my sturgeon has eaten a few pellets after having stopped eating completely. Fingers crossed that whatever affected the water has been removed and that my remaining fish will be well and survive. Thank you all for your comments and advice and I hope never to be in this situation again of losing my beautiful fish.
 
Joined
Jun 11, 2012
Messages
6,960
Reaction score
7,060
Location
Water Valley, Alberta
Hardiness Zone
2a
Country
Thanks for the update.
Keep testing the water and let us know if you have any unusual test results.
 

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Similar Threads

Help me please...koi are dying 175
Koi dying in skimmer 22
Small koi dying, big ones ok. Odd? 14
Petsmart baby koi keep dying 26
koi 1 dead, 1 dying 8
Help my koi are dying 88
New here - all my koi are dying! 4
koi keep dying 7

Top