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Dr. B.
Dr. B., Board Certified Veterinarian
Category: Vet
Satisfied Customers: 22821
Experience:  General practice veterinary surgeon with extensive experience in a wide range of species.
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We have a large white koi with black spots who has always been

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We have a large white koi with black spots who has always been a bit of a character by jumping like a dolphin in the garden pond. About 3-4 days ago he took to laying on one side at the bottom of the pond and although his fins are still moving along with his mouth we fear the worst, what is your recommendation?
& welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.

Again I do apologize that my colleagues could not aid you sooner, but can you tell me:

Are the black spots a new feature or part of his coloration?

Any sores, ulcers, or reddening of the blood vessels in his tail/fins or trunk?
Any belly distension or lifting of scales?
Does he appear to breathing faster or slower then usual?

If stimulated, can he swim normally before settling back to the bottom?

Have you checked your water parameters since this started?
What are your pH, ammonia, nitrites, or nitrates?
Customer: replied 3 years ago.

Black markings part of his colouration
Have noticed the underbelly is pinkier than the rest of him but no ulcers or sores of anytype

Distended belly? hard to tell as he has always eaten well until we stopped feeding them - never stopped him from jumping

Appears to be breathing very slowly

Get very little action from him now - slight wiggle and then lays down

Water is normal has checked at fisheries

Thank you,

First, I am glad to see that the black markings are normal pigmentation , since we can see ammonia burns appear as black discoloration on our fish. Now that is grand that the water parameters were normal but not all places check the same parameters.
Therefore, can you confirm whether nitrites and nitrates were tested and also normal?

Dr. B.
Customer: replied 3 years ago.

We had nitrites and nitrates tested again today and were informed that they were a little high although nothing to worry about however our 'comical fish' has died today and will be missed as he gave us a lot of enjoyment over the years.

Thank you assistancre

I am so sorry to hear that this fish has now passed, Alvira.

Now I have to say that I do not agree that a "little high" is nothing to worry about. Generally speaking, we can cope with 5-10 mg/l but if more than that then we can see nitrate poisoning in fish (and perhaps this poor lad was particularly sensitive as opposed to his pond mates). And the reason I was pressing nitrogenous wastes to be tested is because nitrate toxicity often has this presentation of bottom sitting where the fish can swim normally when prompted short period of time. (where swim bladder fish or those with compression of the swim bladder due to internal abscesses/tumors/enlarged organs would not swim normally). So, I would argue that if this level is even slightly high, it is worth considering partial water changes or treating the pond with a nitrogenous waste blocking product. That way you can ensure that no other fish are potentially at risk.

Furthermore, just to note the other differential signs would be low oxygen levels in the pond. Generally speaking, this time of year many people will turn off filters, aerators, and waterfalls in their ponds. But if the stocking density of fish, size of fish, level of algae in the pond, or temperature warmer (certainly not the case today) are higher then the pond can cope with that delicate oxygen balance, we can also see these kinds of signs and situation. So, you may want to ensure that you do have an oxygen generating feature on in the pond to rule this out.

Finally, I do want to comment on his pink belly. Fish don't tend to discolor the way mammals do. Therefore, this pink discoloration is likely significant and I would be concerned that he may have had a brewing vasculitis (blood vessel inflammation) and bacteremia (bacterial infection of the blood stream). It is possible that this was initiated his bottom sitting and deterioration. Of course, if one of the above was also an issue, it is possible that this was secondary because of the stress those issues would have caused to his immune system. Therefore, we do have to consider this as the reason passing but also make sure that the nitrate levels are corrected and oxygen levels of the pond supplemented in case you have other fish on the brink of coping with these levels.

Please take care,
Dr. B.

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