Pinkish bump on koi's tail


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HI! We're pretty confused about what might be wrong with one of our koi (name of Big Blue). Lots of research, and looking for pictures of something similar, and we're still not quite sure what this is.

We're worried it's tail rot... the bumps are presenting on his tail fin, and bottom fin recently, mostly near his body. They are raised up from the fins and pink/white, kind of pale fleshy colored, with darker pink radiating out from the bumps.

It has been over a month with no serious progression and no open wounds; it does seem to have spread from the top of his tail fin to the bottom. We do not see any signs of it on his body. Behavior is normal; eating, not swimming alone. No flashing. We haven't been able to catch him either to try and isolate. Fast critters.

We added salt and the bump seemed to improve a little over a few weeks, but it didn't go away. It is now looking more prominent than ever. We did have water quality issues recently (debris from bog-filter construction, gap of time between water changes, and an unexpected leak which lead to a 60% water change...).

Anyone have any idea what it is? Or more importantly, how to treat it? We are adding more salt today, and waiting for medi-koi food to be delivered to try and treat potential infection. One of our other koi (Little Blue) is developing a pinkish/orangish color on his tail, but no bumps at all. His (her? lol) belly is also getting some orange color (not pink as far as we can tell), so Little Blue might just be changing colors on us..... darn fish... ♥ None of the other fish seem to have anything resembling these pink bumps on any of their fins.

Fish/Current Environment:
  • Both Big Blue & Little Blue are about 15-16 inches, ~2 years old.
  • We have not added any new fish in over a year
  • pH ~7.8-8.0 steady throughout the day, and since the beginning of the year
  • Ammonia 0.25ppm (the test color is the same as our tapwater (!!??) so it might be our color perception between the strip and the sample; it has been steady all year)
  • 0ppm nitrite
  • 0ppm-5ppm nitrate both steady all year
  • The only changes we've made this summer have been to install bog filters, which mushed around a lot of dead algae, poops, etc. for a few weeks.
  • We have 30 fish in a 5,000 gallon pound (19 koi, 5 sarasa, 4 moors, 2 shubunkin, 1 fantail)
    • We're re-homing some of the goldfish and koi soon (kids gotta move out sometime :D).... if anyone in Southwest Ohio is interested......
Big Blue (with the tail lumps):
big blue.png big blue 003.png big blue 2.png big blue video.png big blue 3.png big blue 004.png

Little Blue (color change or issue?):
little_blue.png

Thank you for any advice, feedback, or hypotheses!!

- tanya & kyle
 
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Meyer Jordan

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Back off the salt. Tail streaks are typically a sign of stress and should abate in short time. Switching to medicated food will not hurt, just limit its use to one week.
Not knowing the timing, but the 60% water change along with all of the other environmental disturbances would certainly have stressed the fish.
If there are no signs of external parasites, the fish's condition should improve quickly.
Sorry but I could detect no 'bump' in any of the photos.
 
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Agree with above though I can see the nodule. Time will heal this if this secondary to stress from the things that happened in the last few weeks that you described.
 
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HI! We're pretty confused about what might be wrong with one of our koi (name of Big Blue). Lots of research, and looking for pictures of something similar, and we're still not quite sure what this is.

We're worried it's tail rot... the bumps are presenting on his tail fin, and bottom fin recently, mostly near his body. They are raised up from the fins and pink/white, kind of pale fleshy colored, with darker pink radiating out from the bumps.

It has been over a month with no serious progression and no open wounds; it does seem to have spread from the top of his tail fin to the bottom. We do not see any signs of it on his body. Behavior is normal; eating, not swimming alone. No flashing. We haven't been able to catch him either to try and isolate. Fast critters.

We added salt and the bump seemed to improve a little over a few weeks, but it didn't go away. It is now looking more prominent than ever. We did have water quality issues recently (debris from bog-filter construction, gap of time between water changes, and an unexpected leak which lead to a 60% water change...).

Anyone have any idea what it is? Or more importantly, how to treat it? We are adding more salt today, and waiting for medi-koi food to be delivered to try and treat potential infection. One of our other koi (Little Blue) is developing a pinkish/orangish color on his tail, but no bumps at all. His (her? lol) belly is also getting some orange color (not pink as far as we can tell), so Little Blue might just be changing colors on us..... darn fish... ♥ None of the other fish seem to have anything resembling these pink bumps on any of their fins.


Fish/Current Environment:
  • Both Big Blue & Little Blue are about 15-16 inches, ~2 years old.
  • We have not added any new fish in over a year
  • pH ~7.8-8.0 steady throughout the day, and since the beginning of the year
  • Ammonia 0.25ppm (the test color is the same as our tapwater (!!??) so it might be our color perception between the strip and the sample; it has been steady all year)
  • 0ppm nitrite
  • 0ppm-5ppm nitrate both steady all year
  • The only changes we've made this summer have been to install bog filters, which mushed around a lot of dead algae, poops, etc. for a few weeks.
  • We have 30 fish in a 5,000 gallon pound (19 koi, 5 sarasa, 4 moors, 2 shubunkin, 1 fantail)
    • We're re-homing some of the goldfish and koi soon (kids gotta move out sometime :D).... if anyone in Southwest Ohio is interested......
Big Blue (with the tail lumps):
View attachment 95321 View attachment 95322 View attachment 95323 View attachment 95324 View attachment 95325 View attachment 95326

Little Blue (color change or issue?):
View attachment 95327

Thank you for any advice, feedback, or hypotheses!!

- tanya & kyle

@TKForever theres nothing at all to worry about and this will heal up nicely on its own given time though they do look distressing .
We call them divits or dings and have seen many of them in our 30 years of koi keeping.
They happen because the koi has knocked itself on either a rock or some object...and as previously mentioned time heals all


Dave
 

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