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Pond koi dying

snailaquarium

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Hi,

A few of our koi have died, 4, we don't know why, one of them looks like it is going rotten, given the time of year people do't really see the pond much, but is there no way of finding out what killed them? It looks dark in patches,
 

Colin_T

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What country are you in?
How long has the pond been set up for?
How long have you had the fish for?
When did they first start dying?
Have you added any new fish or plants in the few weeks before this started?

Have you tested the water for ammonia, nitrite, nitrate and pH?
Does the pond have a filter?
If yes, how often and how do you clean the filter?
When was the last time the filter was cleaned?

Have you done a water change on the pond recently?
How often do you normally do water changes on the pond?
Do you use mains water or well water on the pond?
If using mains water, do you dechlorinate the new water?

Have you got any pictures of the fish?
What symptoms do the fish have?

Has it rained recently?
Has anyone sprayed or fertilised near the pond?
 
OP
S

snailaquarium

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What country are you in?
How long has the pond been set up for?
How long have you had the fish for?
When did they first start dying?
Have you added any new fish or plants in the few weeks before this started?

Have you tested the water for ammonia, nitrite, nitrate and pH?
Does the pond have a filter?
If yes, how often and how do you clean the filter?
When was the last time the filter was cleaned?

Have you done a water change on the pond recently?
How often do you normally do water changes on the pond?
Do you use mains water or well water on the pond?
If using mains water, do you dechlorinate the new water?

Have you got any pictures of the fish?
What symptoms do the fish have?

Has it rained recently?
Has anyone sprayed or fertilised near the pond?
What country are you in?
UK

How long has the pond been set up for?
Years but had decent water changes last summer owing to algae.


How long have you had the fish for?
2 years or so this summer

When did they first start dying?
Within last few weeks


Have you added any new fish or plants in the few weeks before this started?
No changes whatsoever

Have you tested the water for ammonia, nitrite, nitrate and pH?
No but I was about to ask if my testing kit would be of use!


Does the pond have a filter?
Not turned on, don't know why but dad turned it off.

If yes, how often and how do you clean the filter?
When was the last time the filter was cleaned?


Have you done a water change on the pond recently?
No bu t had heavy rain in last two months.

How often do you normally do water changes on the pond?
It had a good clean out two years ago.


Do you use mains water or well water on the pond?
Mains

If using mains water, do you dechlorinate the new water?
No, but this pond is outside and often over flows as result of rain.

Have you got any pictures of the fish?
What symptoms do the fish have?

Blackish in colour, I think where rotting.

Has it rained recently?
Yep.

Has anyone sprayed or fertilised near the pond?
Nope, mum and dad are mystified by it.
 

seangee

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Time to turn the filter on. Its warmed up a lot over the last few weeks. If there are leaves in the pond clear them out.
 

Colin_T

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Test the water for ammonia, nitrite, nitrate and pH.

Clean the filter and get it running.

Do a gravel clean and suck the gunk off the bottom of the pond. If you add mains water, add a dechlorinator to remove any chlorine/ chloramine.

Post pictures of any sick fish and the healthy fish. We might be able to see something on them.
 

PheonixKingZ

Fish Gatherer
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Yes, it looks nasty. Could it maybe be dead algae that got trapped underwater, died, and then decayed?

What are the water parameters of the tank?
 

mjfromga

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When the water is green to THAT extent - you have a problem. The pond looks ultra turbid/dirty. Stuff is floating all in the water, it also looks rather static. Do you aerate? Definitely need to pull any sick fish and get to cleaning out the pond properly. The filters need to be turned on and CLEANED. The fish are in danger. The heavy rains probably kicked up some anaerobic conditions that had settled and it's probably killing the fish.
 
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