White, slimy marks on koi.

[blue_canary]

My parents have a koi pond that they've recently introduced several new koi into to replace ones we've lost during winter the last two years. The first set of new fish was introduced about two weeks ago; a second set, purchased to replace the members of the first set who mysteriously vanished within two days (we're guessing some kind of predator finally stumbled across the pond, as we've never had problems like that before) was added a few days after that, and a third set were added this past week.

This week I noticed that two of our established koi have developed white, slash-like markings on their scales. After much trouble I was able to catch one of the affected fish to take a look at it. The slashes are slightly slimier than the rest of the fish and occur in the same spot on both sides of its tail end. They're also thick enough to completely mask the color of the fish (the fish has a coppery sheen) While I was unable to catch the similarly affected fish, its slashes appear on one side, midway across its body, about an inch apart.

The closest thing I've found like it while researching is carp pox, but I'm not 100% sure that's what I'm looking at. I wish I'd thought to take a picture before I dropped it back in the water! If these symptoms sound familiar to anyone, I'd love to hear any advice or suggestions. Thank you!

 

[CountryEscape]

From the "slash marks" description, and the loss of other fish (you mentioned fish mysteriously disappearing), I would worry it was a predator that missed his catch! I posted on here so I get the responses, as I'm curious to know what others say as well!

 

[fishin4cars]

I would love to see a pic of this. My dealer has a fish about 14" long, It's a Doitsu (scaless Koi) on it's sides it has several diagonal marks on it's sides that really look weird, both sides look identical so this leaves most that have looked at it that it's not a disease or actual skin problem but no one has been able to make any positive identification as to what it actually is. We have had several discussions about this and so far to date no one knows what it is. It's been like this for at least 3 months maybe even longer as that's when we noticed it. It doesn't appear or act sick in any way but it does appear like wrinkles of a old person. LOL, sorry that's the best way I can describe it. It does not appear like anything slimy coming from it but at the same time is does almost look like the skin is pealing???

 

[vertigo72]

Doesnt sound like carp pox to me. Guessing it could indeed be marks of a predator, or perhaps "self mutilation". Do they ever flash? That is, rub against objects..?

BTW, how did they lose fish over winter? If the pond is deep enough and you keep a hole in the ice, there is no reason they would lose fish.

 

[blue_canary]

We do have a variety of common pond predators out here-- blue herons, racoons, cats-- so it's entirely possible something took a swipe at them and those are just the wounds healing up. I'm a bit puzzled as to which would be the culprit though, as we've had fish out there for going on three years now and never had a problem until now.

Do they ever flash? That is, rub against objects..?

Not that I've seen, no.

BTW, how did they lose fish over winter? If the pond is deep enough and you keep a hole in the ice, there is no reason they would lose fish.

Yeah...they weren't exactly aware of that the first few years we had the pond. (we didn't build it ourselves, it came with house, and the old owner had accidentally left one fish behind so we just dropped a few more in there to keep it company) When I was home during winter I did make an effort to melt a hole in the ice periodically, but we still ended up losing about six fish. This last winter it finally occurred to them that if they kept the bubbler running through the winter it would keep a nice-sized hole in the ice. Tada! No more dead fish.

 

[CountryEscape]

Blue Canary, also make sure they know not to try to break the ice, if it does freeze over (say you have an electric outage due to winter storms) as the banging on the ice can kill the fish as well.
Very interesting thread indeed! Hope your fish get better in time. Good luck!