Dead fish.

[RochdaleCowboy]

Hi. Have a 2000ltr pond. 4 waterfalls and a fountain. Mix of Koi, Butterfly and Ghost and comets. Had quite a few die. One at a time over many months. Water tests all show fantastic quality. Do strip tests and full chemical tests. Any ideas what is wrong? One I can deduce had tail rot. I did quarantine, but too late. One or two have damage around mouth. Looks like blood, but can't be wiped off (internal). One looks like his rear has been eaten away. Many thanks in anticipation.

Ian

Ian

 

[WaterGardener]

What are the actual numbers for the liquid tests?

Have you tested the KH?

How many fish were in the pond before this happened and how many of each type were there?

Have you added anything to the pond or had any runoff get into it?

Sorry for all the questions, but we need more information to get a better idea of what could be going on.

 

[Mmathis]

Ditto what @WaterGardener said! As far as the test strip goes, we can’t tell anything because there is nothing to compare the results to. We’d need to see the strip against its reference panel. We find that the liquid drop tests are more accurate, but we always need to know what those “numbers” are.

Just curious, but how long has the pond been up and running? Have you recently made any changes (done a clean out, added new fish, added chemicals)? Do you have a filter?

My best guess is a water quality issue. 2000L is about 525 US gallons. That size might start out OK for smaller koi, but as koi grow, they produce more and more waste products. Your biological filter might just not be able to keep up with converting the waste products. Any time fish get stressed, they are more susceptible to illness.

Without knowing for sure what EXACTLY is going on, I would do small water changes (add dechlorinator if your water is treated). Test the water again, but show the strip against its reference panel.

I know this is devastating, and I hope we can figure it out. Please keep us posted.

 

[RochdaleCowboy]

Thanks for your prompt responses.

Water test results.

pH 8.0

NH3 0

NO2 0

NO3 0

KH 8

GH 14

Equal number of all types. All reasonably small. Biggest was probably the one that has just died. 5-6 inches. Have recently taken out lots of the flag irises, as they were getting too prolific. Have reintroduced some of them with aquatic soil. Deaths were happening before this though. Have AllPondSolutions Pressurised Koi Fish Pond Filter with UV Steriliser Light All in one - Ponds Up to 8000 litres - PFC-8000.

Had 13 fish altogether from around 16. Replaced some of them, only to have them die.

Did treat with this last weekend as thought I had a problem because of previous deaths.

​

 

[WaterGardener]

Thanks for posting that. The water does seem to be in good shape, but your pond was very overstocked.

500 gallons is the minimum amount of water recommended for just one koi, 50 gallons for each goldfish. If they are very small, you can get away with it for a while. The problem is that they grow and quickly.

If you have the chance, please check the gills on a recently dead fish. I hope you don't have that opportunity, but it could also help to find what these fish died from.

 

[Mmathis]

Did you quarantine any new fish that you added? New fish can come in with diseases, and then the stress of being added to a new pond can combine to make the fish sicker. Then, the stresses build up and start to affect the other fish.