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Joan, Vet Technician
Category: Pet
Satisfied Customers: 18642
Experience:  Vet Tech for 35+yrs. Small Animals and Fish
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I have koi, and they seem to be lethargic and not feeling well.

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I have koi, and they seem to be lethargic and not feeling well. today one was on his side and when I picked him up he seemed to have died. after a few seconds he started to move again, hes in a separate tank now and seems to be a little better. need to know whats going on.


My name is XXXXX XXXXX I have been a Vet tech for 30+ years. I have Kept fish for over 40 years. I do need to ask some questions.

Can you tell me was the Koi housed in a pond or in a tank and the size of the tank?

Have you checked the water parameters? Ammonia, Nitrites, Nitrates, and PH?

Is there any bloating of the abdomen?

Any spots on the body?

What size tank is the Koi is the Koi in now?


Customer: replied 4 years ago.

they are in a 700 gallon levels were spots on the koi, and no bloating on the koi. we have gold fish in the same pond and it looks like one may have a little bloating but he seems fine.

Customer: replied 4 years ago.
Relist: Answer came too late.


I am sorry I was away when you had come back. I had been on for four hours and had to take a break.

Did you test the Ammonia, Nitrites and Nitrates and what are the numbers on each? What type of test kit did you use a Test strip or a test tube type water quality test?

Do you have filtration in the pond? Do you have a fountain?

What is the water temperature?

How many fish do you have in the pond? Are they all acting lethargic?

Has the weather gotten warmer, since the fish started to get lethargic?


Customer: replied 4 years ago.

All the fish were lethargic, we have since replaced the water in the pond.all the goldfish have come out of of the koi is fine. but I have two that are still a little lethargic. befor we canged the nitrites, and nitrates were at good levels. our test strip doesn't test for amonia.

test strips were smartpond pond test strips.

we had a problem with a racoon last week, and have set up a fence to keep him out.(electric)have filter and fountain.water was 40 - 50 deg at time.

goldfish have been in pond for 2 years the koi for 1yr.

weather was colder than it had been



Thank-you for the information. The test strips are not very accurate and I suggest using an API Master test kit:

The Test tube type kit is much more accurate. What you are describing with the fish sounds like the Water Parameters were off, leaving the fish Lethargic and causing buoyancy issues which can lead to swim bladder. The Ammonia levels should be 0, the Nitrites 0, the Nitrates 20 ppm or less and the Ph 7.0. If these water parameters are off that causes problems. When you did the water change it helped with the water parameters, but you will need to keep up with them. I would consider doing a 25% water change one a week. You can use the Pond salt in the pond as directed one time because salt does not leave the water. The pond salt will help with stress, bacterial, fungal and paraistic infections in your fish: for maintainence you usually use 2 1/2 cups per 100 gallons of water one time. As far as the Koi you have in a separate tank, you will also have to test the water parameters to be sure that there is no Ammonia spike. The ammonia can jump all the way up becuase the tank is not cycled. This is called new tank syndrome, so you may need to do some water changes to help that Koi start feeling better.

I think once you get the water parameters stable the fish should all start recovering. Please let me know if you have further questions. I am here to assist you and my goal is 100% Excellent Service. Joan

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