goldfish/koi problems

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Fishies86

Aquarium Advice FINatic
Joined
Jan 27, 2011
Messages
793
Location
Isle of Wight, UK
Hi, I've recently taken charge of a huge outdoor pond at work. We had a lot of large koi die on us over the winter and as I'm the person that knows the most about fish at work I'm now responsible for sorting it all out. trouble Is, I have no experience with cold water fish so I need some advice.

When I took over, they had been grossly over fed over the winter with normal fish food. As I understand it, what should have happened is that when the water temp dropped below 10º they should have switched to wheatgerm, then below 4º no food at all. Is this correct? As a result we have some grossly fat fish. They look like they've got an extreme case of dropsy without the pineconing. The ammonia levels in the pond were through the roof, so I immediately stopped feeding them and did water changes every day. The ammonia went down, nitrite went up, then down, and nitrate stayed about the same. The ph was also really low, I'm guessing through it filling up with rain water over the winter?

All the big koi died with no obvious symptoms other than excess mucous. The fattest goldfish (?) Also died, but since the water changes and reduced feeding I haven't had any more die. I'm only feeding them a tiny amount every other day now. Though I've had to have words with other members of staff that the a bucket of food in because the fish were coming to the surface. They were spawning and id already fed them :mad: grr!

Anyway, I've had no more deaths, but I noticed that one of then had developed a red eye, it looks like it's full of blood or something :/ I'm not sure what it is but thought I'd keep am eye on it. The water is really Green at the moment so I haven't seen them for a few days, but when they all came up yesterday for food, there are several others now with blood red eyes and a few have developed red patches on their sides too. It panicked me quite a lot. I don't know what this is or what to do about it. I'm hoping someone will read through my essay and be able to give me some answers because I don't want to lose any more.

I haven't tested the water recently because my test kit is missing after moving house, but I did top up the water yesterday (with water conditioner).
The pond is massive. I think it's about 16000 gallons? It's 6'deep, 6' wide and about 12' long I think. Thank you in advance for any help.
 
Hi! It sounds like you have taken on quite a project here! A few questions first. Who is responsible for the cost of this pond (food, chemicals, etc)? You need to know this first. A proper liquid test kit for the pond is absolutely necessary here. We need to know the exact values for ammonia, nitrite, nitrate and ph before making any further suggestions.

Next, we need to know the exact size and shape of the pond. Is it a rectangle, oval, round or other shape (kidney, etc)? Is it 6ft deep straight down or does it slope? This will give us a better idea of its capacity but I am guessing its in the 2500-3000g range (not 16000!) based on 12x6x6.

Yes, you are correct the fish should not be fed in the winter. Once the temp drops into the low 60's-high 50's some people do switch to a low protein food such as wheatgerm. Generally though, they should not be fed once its @50f or less and not fed again until the pond warms up.

Lastly (this goes back again to who is responsible for the cost here), they will likely need further intervention once water quality issues are addressed and corrected. The issue is here you are located in the UK. Most fish meds are not available without a veterinary assistance (prescription necessary). So, you should also start looking into finding a koi/aquatic vet that specializes in ornamental fish. Please ask any questions!!!
 
Hi! It sounds like you have taken on quite a project here! A few questions first. Who is responsible for the cost of this pond (food, chemicals, etc)? You need to know this first. A proper liquid test kit for the pond is absolutely necessary here. We need to know the exact values for ammonia, nitrite, nitrate and ph before making any further suggestions.

Next, we need to know the exact size and shape of the pond. Is it a rectangle, oval, round or other shape (kidney, etc)? Is it 6ft deep straight down or does it slope? This will give us a better idea of its capacity but I am guessing its in the 2500-3000g range (not 16000!) based on 12x6x6.

Yes, you are correct the fish should not be fed in the winter. Once the temp drops into the low 60's-high 50's some people do switch to a low protein food such as wheatgerm. Generally though, they should not be fed once its @50f or less and not fed again until the pond warms up.

Lastly (this goes back again to who is responsible for the cost here), they will likely need further intervention once water quality issues are addressed and corrected. The issue is here you are located in the UK. Most fish meds are not available without a veterinary assistance (prescription necessary). So, you should also start looking into finding a koi/aquatic vet that specializes in ornamental fish. Please ask any questions!!!


Any food, water conditioner etc. I can take out of stock as we have an aquatic section at work (I work at a garden centre). We have a few meds too, but just the general types.

The pond is rectanglar, with sides that go straight down. Its just like a giant fish tank :) I'll try and measure it all properly tomorrow at work if I have a few spare minutes.

Finding a koi/aquatic vet may be a problem as I live on an island and I'm pretty sure we don't have one on the Island. Will be worth looking into though. If they've got to come over from the mainland thats going to drive up the cost an awful lot and I don't know if the owner is going to be prepared to spend a huge amount. Taking items out of stock is fine, but if he has to actually shell out hard cash he might not be too up for it. We are having an exrtension built at the moment so I think he's planning on getting rid of them anyway, but thats no excuse for letting them get ill and die.

I'll try and dig out my test kit tonight. It must be here somewhere! ;)

Thank you for such a quick reply!
 
Well I think I may have found the problem. Finally found my test kit and these are the results. Rather high nitrates. Glad to see everything else is fine though. Could high nitrates be causing these problems? If so will water changes cure it? Or will they just stop the problem recurring and I'll have to treat it some other way?

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You should start by addressing water quality issues with water changes to bring down the nitrate level. Adding lots of plants will help in the future to keep things stable. High nitrates lowers a fish's immunity, impairs the ability to assimilate oxygen and generally makes them unwell. Lets see how they do once the water quality is under control and go from there! :)
 
Well I've just tested our tap water, and the nitrates are over 20ppm :/ so water changes aren't going to help that much are they? I've been told not to waste money putting plants in because they've tried that before and the fish just eat them. Is there any other way I can get the nitrates down?
 
Even though there are nitrates in the tap, I would not say the a WC is a waste because dilution will bring down the nitrates (and other substances that have built up) to a degree.
As for plants, you could try building a "corral" to keep the koi at bay. It could be as simple as floating a plastic laundry basket to a DIY container using PVC, tie wraps, styrofoam, and bird netting or some type of mesh. Any fast growing floating or unrooted bunch plants (permissible to your region of course) could be used: water lettuce, water hyacinth, anacharis/elodea, Salvinia, duckweed (?)
 
Well I've just tested our tap water, and the nitrates are over 20ppm :/ so water changes aren't going to help that much are they? I've been told not to waste money putting plants in because they've tried that before and the fish just eat them. Is there any other way I can get the nitrates down?

These folks run an aquatics store, and they are worried about the fish eating the plants? Or is this some other kind of store with a pond out back?

The reason I'm asking is that if it's an aquatics store, I've just never heard of an owner/operator that didn't have grow out tanks for plants, and who wouldn't be happy to keep a pond running properly, including having plants in the pond for the fish to eat. It's the way you sell more stuff to your customers...
 
These folks run an aquatics store, and they are worried about the fish eating the plants? Or is this some other kind of store with a pond out back?

The reason I'm asking is that if it's an aquatics store, I've just never heard of an owner/operator that didn't have grow out tanks for plants, and who wouldn't be happy to keep a pond running properly, including having plants in the pond for the fish to eat. It's the way you sell more stuff to your customers...

No it's a garden centre with a pond out the back. We do have an aquatics section, but it's mostly water features. We do sell fish food, a few fish meds, and some pond/marginal plants. We don't sell fish and we don't grow the pond plants, we buy them in. We don't have actually have any oxygenating plants in at the moment, but when we do is £2.50 for three stands of Elodea. The pond out the back is massive so it's gonna take a lot of Elodea to make a difference, and the fish are so big, they're probably going to eat each bunch in two mouthfuls. He doesn't want me to put plants in because they'll get eaten so quickly they won't make any difference so he sees it as a waste of money. We can't put any other plants in because there are no ledges or anything to put them on. The pond is 6' deep with straight sides. Trying to figure something out at the moment. I've done a water change and am in the process of another now, so hopefully that'll bring the nitrates down a lot. Sorry if this post doesn't make much sense, I'm writing it really quickly at work trying not to get caught by the boss ;)
 
Ok well things are definitely looking up :)

I've managed to get the nitrates down to 20ppm. I got sent from the shop a tiny half dead floating hyacinth (I think that's what is called). So I've put that in the pond and its doubled in size already. It should hopefully grow nice and quickly as we are just starting a heatwave and there's lots of nitrogen in the water for it :)

Nearly all the fish are back to normal. There are just one or two with red eyes. I was wondering if perhaps they could have been injuries caused when they were spawning? There are now lots of little goldfish fry in the water so I must be doing something right :) they are also looking more like goldfish than footballs since I've taken over their feeding. Still got the odd few fatties but hopefully they'll slim down a bit soon.

Trouble is, I'm off for two weeks from Monday,so I need to find someone who will feed them what I tell them too,not what they think they should have.
 
Ok well things are definitely looking up :)

I've managed to get the nitrates down to 20ppm. I got sent from the shop a tiny half dead floating hyacinth (I think that's what is called). So I've put that in the pond and its doubled in size already. It should hopefully grow nice and quickly as we are just starting a heatwave and there's lots of nitrogen in the water for it :)

Nearly all the fish are back to normal. There are just one or two with red eyes. I was wondering if perhaps they could have been injuries caused when they were spawning? There are now lots of little goldfish fry in the water so I must be doing something right :) they are also looking more like goldfish than footballs since I've taken over their feeding. Still got the odd few fatties but hopefully they'll slim down a bit soon.

Trouble is, I'm off for two weeks from Monday,so I need to find someone who will feed them what I tell them too,not what they think they should have.

If algae has started to grow on the pond surfaces, they will eat that. They also eat bugs.

You could have someone feed them every 3 or 4 days while you were gone and they'd do fine.
 
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