Lethargic koi

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I am not sure how much of this is relevant but I will give some background just in case.

My mother's pond is about 1200 gallons and is stocked with Koi and gold fish.
We recently netted a lot of the gold fish and have managed to find them new homes as they breed like crazy. To enable us to catch them we removed the water lilies and other weed.

The weed was using up a lot of the pond volume and the koi seemed to really enjoy the extra area when it was out so we decided not to put it back.

A week later however the koi, (7 about 15"-18" long) now just lie on the bottom all packed together. They are no longer eating and rarely move. I have tested for ammonia, nitrite and nitrate with the first tow being zero and the nitrate fairly low.The temperature is cool but not cold. The gold fish seem to be swimming normally although I have noticed that occasionally one or two will jump completely out of the water. The koi aren't doing it now but I got the impression a few days before that they occasionally flashed on the side of the pond. I also noticed that some of the really small gold fish that are still black may have small white patches near their caudal fin. It is only a couple I noticed it on and these fish seemed fine and it could just be their colour.

I am suspecting a parasite but I don't have a microscope and I am not sure I could catch and transport one of the big koi to the vets for them to have a look. From these symptoms can anyone suggest what I should do next?
 

DrDave

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You might want to move the water lillies to lined trashcans filled with city water.

Then treat the pond with salt to .3% salinity. Hold it there for a week then start reducing till you get to .1%. You might be able to put the lillies back then.

The fish that are really bad might need a dip in a 2% solution for 10 minutes to kill the parasites.

I have information on my web site for using salt as a treatment.
 
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Thanks DrDave

I am due to fly out of the country in a week's time for two weeks. If I add salt to 0.3% for the week before I go what do you suggest I do prior to going away for the 2 weeks? i.e. what % can I leave it for those 2 weeks without stressing the fish?

The lilies are history as they took up too much space. There are still 2 dwarf lillies in there and lots of surface cover with water lettuce.

Jono
 
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I have added salt to what I think should be 0.3%. I am not sure what the pond volume is because it isn't an easy shape but I have estimated as best as I can. Just before I go on holiday I will do a 30% water change to reduce it to 0.2%. The pond has a slight leak when brim full so I have asked for a neighbour to keep it topped up which should do a natural slow water change bringing the levels down slowly while I am away. I added the salt over two days so as not to change it too fast.

The koi seemed slightly more active when I went over but still not their normal selves and my mother reports that they still spend a lot of their day huddled on the bottom. I did notice one sad looking gold fish about 4" long. I caught him and brought him home to mine and put him in a 3' aquarium I am not currently using. I have hopefully attached a photo. Does it look consistent with parasite infection? I tested the pond water quality when I did the 2nd salt addition and it remains fine.

Jono
 

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His Pectoral fins are looking a little frayed!? Fin rot?
You never mentioned what your oxygen levels are, especially after removing all that weed, which would have boosted them.
Low oxygen levels can result in sleepy fish.
 

DrDave

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Well if the fish survive your holiday and the fins are the same or worse, you might want to lower the salt content to under .1% and then start treating with Melafix.
 
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The gold fish in the aquarium looks a bit of a state now due to fin rot but I have treated that and it seems to be on the mend. The koi are only slightly more active in the salted pond. The small one (about 5") was leaping out of the water today but the others are still spending most of their day huddled together on the bottom. Some of them seem to have their fins clamped in. Is this a sign of parasites? Their fins look ok as far as I can tell. I have 2 days left before I fly off. If the salt is working should I see some improvement by then? I grabbed a photo of them sitting on the bottom all together. They are about 3 feet deep at the point they are in the photo.

Sorry I don't know how I can tell you what the oxygen levels are in the pond.
 

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Never mind. It was a nice thought. I have the morning free tomorrow so I will see what I can find. If the gold fish seem ok though do you think oxygen can be a problem. I removed about 50 gold fish from the pond so I thought it would be better with the reduced crowding.

I suspect the catching of the ones removed has stressed the koi although they seemed unconcerned and almost flaunted the fact they could swim slowly by the net without needing to worry. I also suspect the removal of the weed has stirred up trouble from the sediment in the bottom.
 

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Once I took one lilly plant out of a goldfish tank, and they sat around like that for two weeks. They might have just gotten scared and need time to get used to the changed pond.
 
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Sadly I have received an email today to say one of my mother's koi is nearly dead. :biggrin: It is currently floating on its side. They had appeared to be doing ok until now and had eaten occasionally and been swimming around. I have asked if once dead it can be frozen so I can take a look at it when I get back. I can only keep my fingers crossed that the others can hold on until I get back on Sunday.

If the problem is parasites am I likely to be able to see them on a frozen fish? I have asked the neighbour to send me a photo if possible so I might be able to post something later to see if you can help me identify the cause.
 

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