unexplained koi death

[fishgirl]

Looking for any ideas! I have a 4500 gal pond with 7 6 small koi. They travel in a pack, eat well, are active and growing. They have 2 caves to hide in, a floating alligator to deter predators, and we do a small water change weekly. All the water parameters are perfect and I have been testing it every 2-3 days. Everything looked great yesterday and last night. This morning when I went to feed them, one was "missing." All the others were hungry, eating, behaving normally. There are 2 waterfalls flowing in the pond but this morning I notice that there seemed to be a wide spread amount of little clusters of white bubbles....I am thinking early spawning activity maybe. Then I start really looking for my missing fish and find it dead, on its side floating on top of the water by the rock edge. No signs of trauma, injuries, disease, nothing. Clear eyes, bright color, shiny scales all laying normally. This fish displayed absolutely no distress signs yesterday or ever. She is a young fish as well, less than a year old. I retested the water again, normal. Watched the other fish and nothing seems abnormal other than the clusters of white bubbles. What in the world could have caused this? I would think if it was a predator I would see injuries and/or it would've been eaten.

 

[Mmathis]

Hello and welcome! We love to have new members, but it‘s always sad when it’s a death or illness that brings them here — I’m so sorry! If you have seen spawning activity, it certainly could have been what happened.

It certainly sounds like you are considering all of the needs for your koi. You mention waterfalls, but what kind of filtration do you have? Do you use any chemicals or additives in your pond?

You regularly test your water, but we need to know what the actual number results were. “Normal” doesn’t really tell us anything as far as trying to help you figure out if this was due to spawning or something else. And what kind of test kit do you use?

 

[poconojoe]

Sorry to here that bad news.

Unfortunately sometimes we may never know the reason for the death of a fish. The fact that (so far) it has only been one fish, leads me to believe it's not an overall problem with your pond, which obviously is a good thing.

Please clarify how many koi you have. Is it 7, 6 or 76, can't tell from the wording. I think something weird happened with the text.

Also you stated they were small koi. What size is small? 2" long? 6" long? 10" long? Be more specific.

The white bubbles puzzle me. I hope no chemicals or soap have gotten into the pond.
Once a friend of mine had a disgruntled son in law put soap in his pond.

I hope your other fish are OK.

Keep us posted.

 

[fishgirl]

I am using the API pond master test kit. Ph 7.5, ammonia 0, nitrite 0, phosphate .25, no chemicals or additives, 3 bottom drain filters that flow through 2 physical filters (one is a large black tub with 3 filter pads and 3 bags of crushed coral, then a smaller physical filter with 2 filter pads at the top of the waterfall) and a small basket strainer, it then travels through 3 large UV lights. Our pond also has a plant only side with water lettuce, hyacyinths and one water lilly....water runs from pond side to this plant side, but fish can't get through. There is one hyacinth that I put on the fish side in case they were spawning. Water is crystal clear right now other than the white clusters of bubbles I saw this morning.....many of which have dissipated later this morning. I also haven't seen the fish chasing each other.

 

[fishgirl]

Sorry to here that bad news.

Unfortunately sometimes we may never know the reason for the death of a fish. The fact that (so far) it has only been one fish, leads me to believe it's not an overall problem with your pond, which obviously is a good thing.

Please clarify how many koi you have. Is it 7, 6 or 76, can't tell from the wording. I think something weird happened with the text.

Also you stated they were small koi. What size is small? 2" long? 6" long? 10" long? Be more specific.

The white bubbles puzzle me. I hope no chemicals or soap have gotten into the pond.
Once a friend of mine had a disgruntled son in law put soap in his pond.

I hope your other fish are OK.

Keep us posted.

I had 7 until this morning....now just 6 since that one died. 7" long in size. We've had them about a month or two and they have doubled in size since we got them.

 

[fishgirl]

Hello and welcome! We love to have new members, but it‘s always sad when it’s a death or illness that brings them here — I’m so sorry! If you have seen spawning activity, it certainly could have been what happened.

It certainly sounds like you are considering all of the needs for your koi. You mention waterfalls, but what kind of filtration do you have? Do you use any chemicals or additives in your pond?

You regularly test your water, but we need to know what the actual number results were. “Normal” doesn’t really tell us anything as far as trying to help you figure out if this was due to spawning or something else. And what kind of test kit do you use?

I accidently posted again instead of clicking reply! So look further down for my answers

 

[poconojoe]

I could be wrong, but I don't think a 7" koi is mature enough to spawn. Plus, I think you would notice the relentless chasing down of the females by the males. So, I think you are correct in that the white bubbles are probably not koi eggs. It is puzzling what they could be though. Did you take any pictures of the bubbles?

 

[j.w]

@fishgirl
Sorry about your fish. Sometimes we don't find an answer to why they die. W/o an autopsy w/your fish looking so normal it is hard to say. It could have had issues from birth. I'd watch the others and just see how it goes.

 

[Jhn]

Bubbles/foam on the water if not due to spawning, is in all likelihood excess DOC’s ( dissolved organic compounds) in the water. Usually due to over feeding...

 

[j.w]

Do the bubbles look like this as my goldfish are spawning again.

 

[poconojoe]

I have seen green bubbles during an excessive algae bloom.

 

[fishgirl]

I could be wrong, but I don't think a 7" koi is mature enough to spawn. Plus, I think you would notice the relentless chasing down of the females by the males. So, I think you are correct in that the white bubbles are probably not koi eggs. It is puzzling what they could be though. Did you take any pictures of the bubbles?

I agree. those were my thoughts too. I didn't take pictures, but will if it happens again....hopefully NOT a fish death but just the bubble pattern

 

[fishgirl]

I have seen green bubbles during an excessive algae bloom.

good thought, but not green and no algae....

 

[fishgirl]

Do the bubbles look like this as my goldfish are spawning again.

View attachment 133067

yes! exactly what it looked like, but I don't see any actual eggs yet

 

[fishgirl]

Bubbles/foam on the water if not due to spawning, is in all likelihood excess DOC’s ( dissolved organic compounds) in the water. Usually due to over feeding...

maybe....but I would think I would see some ammonia then too, wouldn't I?