Koi Fish Dying


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Hi All, my water quality is excellent but my Koi fish are dying off slowly. Every 3 or 4 weeks one dies.
It starts with the scales dropping off and then within a week or so it seems to go whitish with some sort of growth. Also it looks like the fish tail goes red.
I have never had any problems in 15 years.
Any help would be much appreciated.
 

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Hi All, my water quality is excellent but my Koi fish are dying off slowly. Every 3 or 4 weeks one dies.
It starts with the scales dropping off and then within a week or so it seems to go whitish with some sort of growth. Also it looks like the fish tail goes red.
I have never had any problems in 15 years.
Any help would be much appreciated.
Oh Dear that looks awful.
It looks like a bacterial infection to me. At the moment do all the other fish look ok? No signs of distress with them? Are the others eating ok? and they are definately dying one at a time with a few weeks between? Did you introduce anything new a few weeks before this started to happen?
Ray
 
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Thanks Ray, i only have 2 fish left out of 12, so 10 have died and the 2 left seem OK and are eating. I haven't introduced anything new and the pond with those fish have been going for 15 years. The pond had been successful producing thousands of eggs every year.It is strange that its weeks in between, healthy one day and dead within the next couple of days. Unfortunately i live in the only state in Australia which you are not allowed to keep Koi in otherwise i would have had a vet over in a heart beat and at any cost. I'm heart broken at the moment having had those fish from about 2" and now they are all/were over 20".
Ange
 
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Thanks Ray, i only have 2 fish left out of 12, so 10 have died and the 2 left seem OK and are eating. I haven't introduced anything new and the pond with those fish have been going for 15 years. The pond had been successful producing thousands of eggs every year.It is strange that its weeks in between, healthy one day and dead within the next couple of days. Unfortunately i live in the only state in Australia which you are not allowed to keep Koi in otherwise i would have had a vet over in a heart beat and at any cost. I'm heart broken at the moment having had those fish from about 2" and now they are all/were over 20".
Ange
Oh dear such a tragedy. Have you added any chemicals at all? Any medicines etc?
I am also in Australia and was unaware that any state prohibited Koi?
Ray
 
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I'm in Victoria. I wouldn't know what chemicals to add unfortunately.
 
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Oh dear such a tragedy. Have you added any chemicals at all? Any medicines etc?
I am also in Australia and was unaware that any state prohibited Koi?
Ray
I would add Melafix in accordance with the instructions as soon as you can.
Ray
 
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you can get Melafix at any pet store. It is a really gentle and natural antibiotic. It does not kill good bacteria if used correctly. I would use it in your case given there is no accurate diagnosis.
 

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Hello Ange- So sorry for the loss of your fish! I agree with Ray G about it being a bacterial issue. If you can get the Melafix and possibly Pimafix, those would be good treatments.
As to why your koi are dying- can you give us the information on your pond? Size of pond, GPH of pumps, filtration, actual test results and you said your koi laid thousands of eggs, do you have any other than the 2 left?
The one thing that always changes in a pond over time is the size of the fish! A 4" koi produces very little waste- a 20" can overwhelm a filter quickly!
Is it possible that something has washed into the pond or been sprayed nearby that could have been harmful- pesticides, herbicides?
Again- so sorry for the lost fish-
 

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@Ange
Very sorry for you losing your fish. Hope you can somehow save the last two. I guess we never know what kind of germs can enter our pond, from possible birds flying over,landing in or near the water or who knows?
 
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You mentioned your water quality was excellent, do you own a microscope ? If so, I'd do a scrape and scope on the remaining two fish for parasites. Secondary bacterial infections can develop where they enter the fish, ad the infection spread, becoming an ulcer.

I agree with above advice about adding a broad spectrum antibiotic treatment like Melafix. I'm really sorry for what you're going through and it's particularly frustrating to not be able to keep koi in your country.
 

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Welcome to our forum, good advice above. I have never had koi so can't really help with diseases.
 
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you can get Melafix at any pet store. It is a really gentle and natural antibiotic. It does not kill good bacteria if used correctly. I would use it in your case given there is no accurate diagnosis.
you can get Melafix at any pet store. It is a really gentle and natural antibiotic. It does not kill good bacteria if used correctly. I would use it in your case given there is no accurate diagnosis.
Thanks mate . i will get some Melafix this morning.
 
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Hello Ange- So sorry for the loss of your fish! I agree with Ray G about it being a bacterial issue. If you can get the Melafix and possibly Pimafix, those would be good treatments.
As to why your koi are dying- can you give us the information on your pond? Size of pond, GPH of pumps, filtration, actual test results and you said your koi laid thousands of eggs, do you have any other than the 2 left?
The one thing that always changes in a pond over time is the size of the fish! A 4" koi produces very little waste- a 20" can overwhelm a filter quickly!
Is it possible that something has washed into the pond or been sprayed nearby that could have been harmful- pesticides, herbicides?
Again- so sorry for the lost fish-
Thanks. The pond is 2000 litres with a 4000 litre gravity filter. When they have there yearly spawn i don't separate the eggs, so therefore they quickly get eaten up and become fish food. I have maintained a balance of about 12 fish not to over crowd the pond and they have been at the size they are for the last 3 years. I will get some Melafix and give it a go on the last 2 fish.
 
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You mentioned your water quality was excellent, do you own a microscope ? If so, I'd do a scrape and scope on the remaining two fish for parasites. Secondary bacterial infections can develop where they enter the fish, ad the infection spread, becoming an ulcer.

I agree with above advice about adding a broad spectrum antibiotic treatment like Melafix. I'm really sorry for what you're going through and it's particularly frustrating to not be able to keep koi in your country.
Thanks. They are legal in most states of Australia but not Victoria where i live. its ridiculous.
 
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Thanks. They are legal in most states of Australia but not Victoria where i live. its ridiculous.
I believe it is illegal to own koi or gold fish in the state of Maine, here in the U.S.
 
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Thanks. They are legal in most states of Australia but not Victoria where i live. its ridiculous.
Yes it is! Try goldfish as there are many types and colours now and many look like koi in body shape.
 
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Yes it is! Try goldfish as there are many types and colours now and many look like koi in body shape.
I might try Goldfish. The only thing is that they don,t get to the same size of Koi.
 
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I might try Goldfish. The only thing is that they don,t get to the same size of Koi.
Do you have shubunkin? They grow fairly large ( not as big as koi ) and are quite beautiful with long flowing fins.
 

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