Lost all my beauties!

[Tula]

Sorry for the loss of your fish. You've already received good advice, asking you basic questions so we can help you.

 

[j.w]

@Mattr
Can't help w/diseases but that does look horrid and I sure hope you can figure out what it is so it doesn't keep happening to any fish you have left or any new fish down the road.

 

[Mattr]

Thank you all for the kind wishes and excellent help! Hopefully we can figure this out!

 

[IPA]

Sorry about your fish. Ulcers are generally caused by bacteria. Koiphen forum has an emergency koi health thread, I recommend checking them out. A a Get a test kit (not strips) ASAP. The API Pond Master is an affordable and good one, also get the GH/KH test kit. Order from Amazon, Chewy, etc or get it locally if you can find it. Until you know the water quality issue I would hesitate to begin any treatments, but you need to do that ASAP also. Maybe a good pond store or pet store can test your water and the important test needed are pH, Ammonia, Nitrite, KH and water temperature. If all those levels are good (pH is reliant on KH so if KH is at least 100 whatever pH is is likely acceptable. KH of 150-200 is what you would like.)
You can test for O2 but those test are harder to come by and can be pricey. Ensure you have good aeration and not an excessive amount of rotting material in the pond and filters and there shouldn’t be an O2 issue.
google “koi ulcers “ , do a photo search and you will find a lot of helpful websites. The ulcers on your fish, fatal, are more severe than most I saw. Likely some of the remaining koi have ulcers and need treatment ASAP but again you want to address the water quality issue before you begin treatment. Don’t just trust the miracle treatment even reputable pond dealers will sell you, do the research and decide which of the treatment options are going to be best for your particular situation and ability to manage the treatment.
Kophien is a dedicated Koi forum more focused on the purest Koi pond than the mixed plant and fish water gardens we keep. Check them out, do some research on some of the koi health sites, address the water quality issue and treat for the infection.

edit: to add, if you do not have many plants a test for nitrate and possibly phosphate would also be recommended.

 

[Mattr]

Thanks very much for this help! Are these in fact ulcers?

 

[IPA]

According to the definition I pulled from the web “Most commonly, fish get skin ulcers. This is an open wound in the skin of a fish that may expose the underlying musculature. In fish, it can be accompanied by scale loss, local growth of fungus and may appear suddenly or grow slowly over time. They can appear anywhere on the body of the fish” I’d say they are ulcers.

 

[Mmathis]

@Mattr How long has this pond been up and running, and have you recently added any new fish? Any predators?

 

[Mattr]

Understood. Thank you ! It’s a little hard for me to accurately tell. I’m not sure what I’m looking at!

 

[Mattr]

@Mattr How long has this pond been up and running, and have you recently added any new fish? Any predators?

The pond is at lest 20 years old. All of these fish were added a few weeks ago, given to me by a neighbor who ran out of room in his pond

 

[Mattr]

We do have raccoons and possums and LOTS of birds

 

[Mattr]

Predators were my first thought but the nature of the injuries don’t really seem to claw marks. Not a lot of gashes and ripped fins

 

[Mmathis]

The pond is at lest 20 years old. All of these fish were added a few weeks ago, given to me by a neighbor who ran out of room in his pond

Did you quarantine these fish before you added them? Just wondering, because stress can lead to illness — but that doesn’t mean that you did anything wrong, but it does make me wonder if the fish were already compromised. Did any of them show signs of an injury?

Your pond is 20 years old! That is awesome! Is it lined or natural? Yes, trees can be a problem, but you’re handling that well. We would LOVE to see pictures of your ponds!

 

[Mattr]

I didn’t isolate them and should have. I didn’t see any sign of injuries though.
Here is my pond!

 

[Mmathis]

Predators were my first thought but the nature of the injuries don’t really seem to claw marks. Not a lot of gashes and ripped fins

The size of an injury can be deceiving. What about sharp rocks?

 

[Mattr]

The size of an injury can be deceiving. What about sharp rocks?

I honestly don’t know...same rocks that have always been in there really. The only change I made was to the falls and stream and that was months ago. I didn’t add any rocks to the inside of the pond just the falls