Koi Fish Died - Help Save others in the pond!

[Hugo.Pahwa]

Hi Everyone,
I discoved one of my koi's dead this morning.
My pond is about a 1200 gallons with three 8" Koi. They overwintered well and everything seemed perfectly until yesterday. This morning I found one of the Koi floating on its side with it's belly near pectoral fin, cut open with it's guts out. What could this be? A disease/parasite or an injury? Im worried sick about the other two Koi's now. What can I do?
PLEASE HELP!

Thanks,
Hugo

[ademink]

Hard telling from this stage. If I had to hazard a guess, it may have had a significant ulcer and it finally had a "breach" in its body, allowing the innards to come out. Are you positive it was "alive and well" yesterday? This fish appears to have been dead (or really ill) for quite some time from the condition of the fins and the eye.

[richtoybox]

I agree with Andrea, this appears to have come from a significant ulcer. Belly ulcers are hard to see until they are very extensive. The cause is bacterial, which may have come from parasites breaching the skin, or abrasion of the skin from the fish laying on the bottom of the pond over the winter. I would try to get a good look at the bellies of the other fish to assure myself that there are no others having similar issues. If you find similar issues, please let us know so we can help with treatments.

It would be beneficial to provide numbers for the test results, preferably drop type test kits, for ammonia, nitrite, nitrate, high range pH, KH, and temperature. The water is the environment that the fish have to live in and we would like to assure that the environment is the best that it can be.

[Hugo.Pahwa]

Thank you Andrea for your reply. The water is still pretty cold, and the fish haven't entirely woken up yet, so not a lot of movement. The fish appeared to be alive yesterday, but it's entirely possible that it was already dead and hadn't surfaced yet.

[Hugo.Pahwa]

Thanks so much for your reply. This is incredibly helpful! I really hope the others don't have similar issues. This was my pond's first winter, and I really hope my lack of knowledge and inadequate winter care didn't cause this. I'll have a look at the others, test the water and get back with numbers.
I appreciate all the help - Thank you!

[Hugo.Pahwa]

Hi RichToyBox,
Just tested the water and got these results.

PH: 9.0 + ( Dont know why this happed, I added some pond salt before winter)
Ammonia: 0.00 PPM
Nitrite: 0.00 ppm
Phosphate: 0.25 ppm

Thanks

[richtoybox]

Was the pH run with a high range test kit, a wide range test kit, or a dip strip? Dip strips can be very undependable, and the wide range pH test is designed to tell you whether you need the regular pH, or the high range test kit. Its values are too far apart to be of much use otherwise. If you haven't, I would invest in a KH test kit as it is the one test that I relied on most, once I had the filters cycled. A good KH of over 100 and up to over 300, means the pH is pretty stable, which makes the filter bacteria happy and that makes the fish happy, as well as not having pH jump around potentially burning the fishes gills.

[spkennyva]

This fish appears to have been dead (or really ill) for quite some time from the condition of the fins and the eye.

Totally agree. It sure looks like this fish has been dead for a while. A recent death doesn't show (at least in my experience) the level of decay like that in the photo.