Having trouble with diagnosing the problem

[Charlie West]

New member here and would welcome some help from all the lovely knowledgeable people on here please.

We have a 12,000 litre sunken garden pond with approx. 20 fish, all koi aside from 2 shubunkin. It has a waterfall, skimmer box, pump and filter, UV lights etc (can get more specifics on these when husband is home) water is therefore well oxygenated and parameters are good. We use the NT labs water test kit so therefore no exact numbers but all nitrite, ammonia etc levels appear to be showing as all good. Never had any trouble with our pond, and have had happy healthy fish until recently. Thinking about investing in a better water testing kit which shows the numbers of each water parameter.

About 5 or 6 weeks ago we introduced 4 new koi to the pond without quarantining them. They came from a friends garden pond. Big mistake and very naive on our part. Since the new arrivals we have lost 3 koi, one of which we've had for 6 years and was about 12", this was devastating. At the time of introduction of the new fish, one koi hid in the rocks and unbeknown to us subsequently died and lay in the rocks for some time. Once we realised, we got him out, drained the entire pond, jet washed it all out, refilled with the hose and used aquasafe, putting all the fish back in once there was enough water in there.

Our remaining fish all seem to now have a problem with white patches on their bodies like a candle wax appearance (carp pox?) and are either hanging in the water or lying on the bottom with fins clamped to their bodies, lots of flashing going on, many are hiding in the cave or hanging near the bottom of the waterfall, none are gasping at the surface. They are not overly interested in feeding although if we leave them alone at feed time the food all gets eaten. Some of the lighter colour fish are also taking on a pinky coloured hue. Initially we thought this was white spot and we treated with acriflavine, 2 doses so far. I now think this is something else but don't have the knowledge or microscope etc to find out exactly what. Google is quite the minefield! I'm really worried that we will lose more fish and would really like some advice as we are at a loss, and have spent quite a bit of time and money trying to resolve the issues. Im now worried that we are treating for the wrong thing and therefore throwing chemicals into the water which aren't tackling the problem.

Can anyone advise on the best course of action? I have attached pictures of the white patches which we believe all the fish have to varying degrees.

Thankyou for reading my post.

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[j.w]

@Charlie West
Not familiar on Koi diseases but that's a pond w/about 3000 + gals of water and not very big for that many Koi depending of course on how big they all are right now. Not saying that is your problem but it could be. Otherwise like you said you added new fish w/o quarantine and you just never know about issues. I'll let someone else help you w/your symptom descriptions.

 

[WaterGardener]

If you could get liquid type testing kits it would help us a lot. Be sure to get a test for KH, pH, ammonia, nitrite, and nitrate.

Please test the water and post the results here.

 

[Charlie West]

View attachment 159914@Charlie West
Not familiar on Koi diseases but that's a pond w/about 3000 + gals of water and not very big for that many Koi depending of course on how big they all are right now. Not saying that is your problem but it could be. Otherwise like you said you added new fish w/o quarantine and you just never know about issues. I'll let someone else help you w/your symptom descriptions.

Thankyou for the welcome! We have one large koi 18", 2 rainbow koi 12" the rest are fairly small in comparison. Everything went wrong after adding the new fish which is the likely cause of issues. Hopefully someone can help with advice on here.

 

[Charlie West]

If you could get liquid type testing kits it would help us a lot. Be sure to get a test for KH, pH, ammonia, nitrite, and nitrate.

Please test the water and post the results here.

Thankyou, we have ordered a test kit this evening as our original test kit only tested for 3 of the parameters. The new one tests for 6, including those you mentioned so I'll post the results here as soon as it arrives.

 

[Mmathis]

Hello and welcome! Please don’t drain and clean your pond again! By doing this….you have destroyed a big chunk of your beneficial bacteria….which makes the fish more susceptible to problems. Yes, please check your water and get back with us. I don’t mean to come across as mean, so I apologize (trying to eat and type…with a cat attempting to grab my food, so sentences are short.).

So sorry this has happened to you, but glad you came here for help.

 

[GBBUDD]

@Ian when i click on the photos above i get this message
Oops! We ran into some problems.
You do not have permission to view this page or perform this action.

 

[Charlie West]

Hello and welcome! Please don’t drain and clean your pond again! By doing this….you have destroyed a big chunk of your beneficial bacteria….which makes the fish more susceptible to problems. Yes, please check your water and get back with us. I don’t mean to come across as mean, so I apologize (trying to eat and type…with a cat attempting to grab my food, so sentences are short.).

So sorry this has happened to you, but glad you came here for help.

Hi there! Thankyou for your message! I think it was a panic reaction when we emptied the pond, thinking that the dead fish was contaminating the water as other fish were dying the water smelt bad too. We did keep quite a large portion of existing water (maybe 30% in the holding pond) and then topped back up with tap water. I wonder if getting rid of beneficial bacteria has exacerbated the issues. Its so difficult to pinpoint what went wrong thankyou for taking the time to reply even with a hungry cat on your lap! Will post water parameters ASAP.

 

[GBBUDD]

just doing a water change won't mean you killed of the bb in your pond. bb is more on things like your rocks. And if the water smelled like rotten eggs then you made the right call.

 

[Lisak1]

I wonder if getting rid of beneficial bacteria has exacerbated the issues.

It could, but like @GBBUDD said it wasn't so much the water change as it was the jet washing - if you mean power washing. The rocks are home to a whole lot of beneficial bacteria and even the algae that grows on them is part of your ponds natural filtration.

And if the water smelled like rotten eggs then you made the right call.

Agree with that - but one dead fish wouldn't foul the entire pond. If it suddenly smelled that bad, then something else was going on.

1. Adding new fish is always always ALWAYS a risk to an existing pond. Even if you quarantine the fish, the new fish can bring something into the pond that THEY are perfectly adapted to, but that can affect your existing fish. Or vice versa - your fish are used to your pond and all the things that might live there - the new fish only encounter that environment when you toss them in. Quarantining can identify obvious health issues, but there's definitely more to the equation. So while it is best practice, please know it's not foolproof.

2. Water changes in and of themselves are stressful for fish. Especially when you completely empty a pond. Adding some of the old pond water back is good, but makes no sense if you are emptying the pond because you think the water is bad.

3. So combine new fish (which stress out the old fish), new water, now add a host of chemical "fixes" - more stress. And what happens to stressed out fish? They get sick.

What makes fish sick? Parasites of all kinds is one issue, but poor water quality can lead to all kinds of things like ulcers, funguses, etc. Having too many fish in too small a volume of water is without enough filtration is generally a precursor to all kinds of fish problems. You had far too many koi in your pond to make that a sustainable situation. A 3000 gallon pond is great for lots and lots of shubbies and goldfish. Or a couple of koi. I prefer the former!

The comment we hear ALL THE TIME is "my pond and fish have done fine for XX years! What happened??" What happened is your fish continued to grow and continued to put more and more stress on the environment in the pond. What didn't change - the volume of water and the size and type of filtration - the two most important factors is determining how many fish can live in your pond.

You likely reached what we often call "the tipping point" - that moment in time where the balance shifted from "everything is great!" to "we're in crisis mode" and the first visible sign is always the fish - the get sick, they die. And it happens fast. Before you can even realize what's happening your fish are dying or dead and you're scrambling to figure out what to do. Nature has already figured it out - the population needs to be reduced.

Adding more fish to an already overstocked pond pushed the ecosystem right over the edge, but I don't have to tell you that. You're sadly living with the results. And that stinks.

Best approach in my mind? Wait and see what happens from here. Fewer fish in the pond is a good thing at this point so even though it's sad that your fish are dying, it's going to make managing the pond in the future easier. If the fish survive, your best approach is to start re-homing them. They need more space than you have to offer. Or start digging and make the pond larger!

I can't see the photos you posted, but if those white patches are fuzzy looking, thats fungus. You can treat that, but you need to make sure thats what it is before you start putting more stress on the fish. Koi pox appears like white waxy looking bumps - if it's that, there's no issue. It's not harmful to the fish.

A bit more information on your filtration will help. What kind of filter are you using? What's your maintenance routine? When you get that test kit and can post actual numbers that will help as well.

We're here for you! We've all had issues of one kind or another over the years and understand the frustration and feeling of helplessness. Stick with us and we'll work through it together!

 

[Charlie West]

It could, but like @GBBUDD said it wasn't so much the water change as it was the jet washing - if you mean power washing. The rocks are home to a whole lot of beneficial bacteria and even the algae that grows on them is part of your ponds natural filtration.


Agree with that - but one dead fish wouldn't foul the entire pond. If it suddenly smelled that bad, then something else was going on.

1. Adding new fish is always always ALWAYS a risk to an existing pond. Even if you quarantine the fish, the new fish can bring something into the pond that THEY are perfectly adapted to, but that can affect your existing fish. Or vice versa - your fish are used to your pond and all the things that might live there - the new fish only encounter that environment when you toss them in. Quarantining can identify obvious health issues, but there's definitely more to the equation. So while it is best practice, please know it's not foolproof.

2. Water changes in and of themselves are stressful for fish. Especially when you completely empty a pond. Adding some of the old pond water back is good, but makes no sense if you are emptying the pond because you think the water is bad.

3. So combine new fish (which stress out the old fish), new water, now add a host of chemical "fixes" - more stress. And what happens to stressed out fish? They get sick.

What makes fish sick? Parasites of all kinds is one issue, but poor water quality can lead to all kinds of things like ulcers, funguses, etc. Having too many fish in too small a volume of water is without enough filtration is generally a precursor to all kinds of fish problems. You had far too many koi in your pond to make that a sustainable situation. A 3000 gallon pond is great for lots and lots of shubbies and goldfish. Or a couple of koi. I prefer the former!

The comment we hear ALL THE TIME is "my pond and fish have done fine for XX years! What happened??" What happened is your fish continued to grow and continued to put more and more stress on the environment in the pond. What didn't change - the volume of water and the size and type of filtration - the two most important factors is determining how many fish can live in your pond.

You likely reached what we often call "the tipping point" - that moment in time where the balance shifted from "everything is great!" to "we're in crisis mode" and the first visible sign is always the fish - the get sick, they die. And it happens fast. Before you can even realize what's happening your fish are dying or dead and you're scrambling to figure out what to do. Nature has already figured it out - the population needs to be reduced.

Adding more fish to an already overstocked pond pushed the ecosystem right over the edge, but I don't have to tell you that. You're sadly living with the results. And that stinks.

Best approach in my mind? Wait and see what happens from here. Fewer fish in the pond is a good thing at this point so even though it's sad that your fish are dying, it's going to make managing the pond in the future easier. If the fish survive, your best approach is to start re-homing them. They need more space than you have to offer. Or start digging and make the pond larger!

I can't see the photos you posted, but if those white patches are fuzzy looking, thats fungus. You can treat that, but you need to make sure thats what it is before you start putting more stress on the fish. Koi pox appears like white waxy looking bumps - if it's that, there's no issue. It's not harmful to the fish.

A bit more information on your filtration will help. What kind of filter are you using? What's your maintenance routine? When you get that test kit and can post actual numbers that will help as well.

We're here for you! We've all had issues of one kind or another over the years and understand the frustration and feeling of helplessness. Stick with us and we'll work through it together!

Hi LisaK1, Thankyou so much for your informative reply you have given us lots to think about (this is a good thing!) We did jet wash as we had an unusually high growth of blanket weed anyway, fortunately algae on rocks is now returning as its been a couple of weeks since the water change and we've had UV lights off while treating with acriflavine.

1. This makes perfect sense. Introducing the new fish will have upset the equilibrium in our pond by distrupting what the new fish are used to or by the new fish introducing something ours are not used to. Hard lesson learned there, we will not be introducing any more fish. If anything we will have to rehome some of them, once issues are sorted.

2 &3 We naively thought that one dead fish had fouled the whole pond, we thought that whatever that fish died from, was then spreading to the others, killing them. Add to that the stress that then followed and we weakened our fish, making them susceptible to all sorts

I wouldn't say we were complete beginners, having had a pond of some sort for 6 years, but we are certainly not experienced either. It's this situation that has illustrated this fact and has us going along this steep learning curve. We just want to do our best for our fish and try to be responsible in looking after them. We do feel we have failed here but I guess so does everyone to some degree at one point or another.

We honestly thought that our pond was not overstocked based on a calculation of 2kg of fish per 1000 litres. They don't "look" overcrowded and many of them are relatively small (6") again, a rethink on this will be necessary. That "tipping point" you mentioned i would agree has been breached and so now we try to fix it. The white patches are not fuzzy so hopefully we can rule out fungus. A wait and see approach I think is for the best and we will test the water ASAP. Our filter is a Bioforce on the skimmer box with a 6,000 litres an hour pump, the waterfall box has live media alfagrog with layers and sponges in a 240 litre tank which filters from the top down. I hope that makes sense.

Thanks again for your insight and help, we really appreciate forums like this and the experience that can be offered from its members and ultimately we hope we can get back to a happy, healthy and balanced pond once again.

 

[Charlie West]

If you could get liquid type testing kits it would help us a lot. Be sure to get a test for KH, pH, ammonia, nitrite, and nitrate.

Please test the water and post the results here.

Hi everyone, the test kit arrived and the numbers are as follows: (Apologies if I've posted to the wrong place.)

PH 9
Ammonia 0
Nitrite 0.25
Nitrate 8.0
KH 12 drops
GH 23 drops

We are in a hard water area in SE England. Nitrate is possibly the issue here? Would welcome any thoughts if my concern is correct and how I would ideally go about resolving this.

Many thanks to you all for all the replies I've had so far and for your willingness to help us out

 

[Mmathis]

I honestly can’t think of a solution, only preventive measures for going forward.

As you’ve already discovered, adding new fish (non-quarantined) is probably what started the problem.

Then, your pond is just over 3000 gallons, so you started out this scenario with close to 20 koi. I’m not saying you were already overstocked to begin with (well, yes, I guess I am…..), but by adding more fish (whether they were quarantined or not), you have added to the amount of waste that your biofiltration can handle.

Then, by cleaning the pond, all of the good bacteria have been destroyed, so you are basically starting over with an un cycled pond.

Without a scrape and scope, it’s hard to way WHAT the offending organism is that is attacking the fish…..but water quality is the primary issue.

Not sure about your test results….if I didn’t know better, I would think your pond is cycled. pH is high, but KH looks good. Fish can adjust to the pH as long as it remains stable (with no shifts — a good KH helps here).

How many fish (koi) are still in the pond? Are they still sick?

For now: Water changes and close water monitoring……? Reduce the fish load…..? No suggestions on how to treat the sick fish……sorry….

 

[Charlie West]

I honestly can’t think of a solution, only preventive measures for going forward.

As you’ve already discovered, adding new fish (non-quarantined) is probably what started the problem.

Then, your pond is just over 3000 gallons, so you started out this scenario with close to 20 koi. I’m not saying you were already overstocked to begin with (well, yes, I guess I am…..), but by adding more fish (whether they were quarantined or not), you have added to the amount of waste that your biofiltration can handle.

Then, by cleaning the pond, all of the good bacteria have been destroyed, so you are basically starting over with an un cycled pond.

Without a scrape and scope, it’s hard to way WHAT the offending organism is that is attacking the fish…..but water quality is the primary issue.

Not sure about your test results….if I didn’t know better, I would think your pond is cycled. pH is high, but KH looks good. Fish can adjust to the pH as long as it remains stable (with no shifts — a good KH helps here).

How many fish (koi) are still in the pond? Are they still sick?

For now: Water changes and close water monitoring……? Reduce the fish load…..? No suggestions on how to treat the sick fish……sorry….

Hi Mmathis, thanks for your reply. Unfortunately I'm not confident enough to scrape and we don't have a scope either. Unsure as to whether my husband wants to buy a microscope, he's nearly at the point of giving up with the pond entirely to be honest.

Our pond is cycled, if by that you mean by how the pump and filter works? So the water is continuously being cycled round the pond. We now have 17 fish, 2 have died today, small ones, no outward signs of anything wrong. And one is barely holding on, has a furry growth on his belly and has lost his ability to swim. I think he's past the point of help sadly.

We will do partial water changes and keep monitoring...feeling pretty defeated at this point

 

[Mmathis]

@Charlie West “Pond cycling,” the way we refer to it, is a series of processes that happen over time (weeks or longer), where you have a “nitrogen cycle” take place, where different bacteria (beneficial bacteria, not the kind that cause disease) act on waste materials in the water (produced by the fish and/or by rotting organic waste), converting them from toxic ammonia to nitrates, which are safe. Maybe, I should have said NITROGEN CYCLE to begin with. Sorry.

As for the microscope reference, that’s only useful if you are trying to treat a SPECIFIC disease on the fish. Different meds treat different diseases. No, not suggesting you get a microscope, just saying that in order to treat the fish, you need to know WHAT you’re treating. I think you are past that point.

Please don’t give up! We all know how frustrating this can be. Can you get rid of about 1/2 the fish you have now? Not to sound cruel, but the sicker ones can be humanely euthanized……….but your fish load needs to be reduced. 3000 gallons is only meant to contain a few koi (3 or 4 at most).