Fish In Pond Are all Dying

Dave

Distinguished Member
Hi all, I'm sure there'll be someone who knows their fishy stuff around here so any help would be great.

I recently buggered off to spain for a couple of weeks and on my return I found 4 of my pond fish dead (all ghost koi) the rest seem to be slowly dying too.

I got the water tested and the PH is 5.5, Nitrite 1 and Ammonia 8. The shop gave me some stuff to stick in the pond and said it should sort it out.

The thing is it's never happened before in the 2 or so years I've had the pond and I can't see anything that would have caused it unless one of the fish died and then being left for 2 weeks with the others killed the rest off, I'm at a total loss.

The other thing is, seeing as I now only have 4 fish left and in all likelihood they are not going to make it, what should I restock it with? I've read that koi are wrong for a small pond (it's around 35cm deep and 3 ft in diameter) but goldfish are ammonia machines so what species should I be looking at.

Cheers, Dave.
 

WibXL

Well-known Member
Any ammonia in the water is bad for fish but if it's at 8 I can't see them lasting much longer. You could try changing half the water in the pond for fresh water treated with a chlorine remover and then add a product like ammolock which will lock the ammonia into a safe form until it's gone.

Really though you need to know what caused the ammonia spike in the first place as you need to remove the cause as well as treat the symptom. Overstocking, overfeeding, inadequate filtration, too much decaying organic matter in the water can all case an ammonia spike as can a fish dying of natural causes and then being left in the water to decay.

Also have a read up on the nitrogen cycle if you haven't already as it will give you a good understanding of what's happening.
 

Dave

Distinguished Member
Any ammonia in the water is bad for fish but if it's at 8 I can't see them lasting much longer. You could try changing half the water in the pond for fresh water treated with a chlorine remover and then add a product like ammolock which will lock the ammonia into a safe form until it's gone.

Really though you need to know what caused the ammonia spike in the first place as you need to remove the cause as well as treat the symptom. Overstocking, overfeeding, inadequate filtration, too much decaying organic matter in the water can all case an ammonia spike as can a fish dying of natural causes and then being left in the water to decay.

Also have a read up on the nitrogen cycle if you haven't already as it will give you a good understanding of what's happening.

Cheers for that, I simply can't see what what would make the ammonia levels go up so much. I've changed some of the water, it's not overstocked at all ( 7 fish in a 50 gallon pond), they have been fed nothing while I've been away so it can't be overfeeding, there is no organic matter decaying (except the fish that were dead when I got back).
 

johnny70

Well-known Member
Ammonia will be from the dead fish I would expect. Do as advised above, water change and some Ammolock to reduce the toxicity of the ammonia, keep testing and keep changing water until the water is back to normal. I take it you have checked the pump to make sure its working ok?
 

deckingman

Novice Member
I'd go over to pfk (Practical Fishkeepers) site and check out their forums and/or register and post your question there. Lots of experts over there.
 

HMHB

Distinguished Member
That PH is too low as well, fish do not like acidic conditions. You can buy shells to regulate the PH of your water.
 

HMHB

Distinguished Member
I keep all my pumps running and I keep the UV filters switched on as well. I'd rather keep water running through the filters so they aren't starting totally from scratch again in the spring.
 

Retro Techno

Active Member
Without wishing to repeat a lot of the advice that has been given, I thought I'd flex my fish muscles for the first time in a year, so...

Unless someone has been overfeeding your fish in your absence it'll be hard to find a culprit.
My first culprit would be the acidity of the water. A pH of 5.5 is too low for most common coldwater carp species. A pH of 7.0 to 8.5 would suit them best, although they can tolerate temporary deviations.
Luckily, if you can say that, ammonia (NH3) becomes far less toxic in acidic conditions as it gains an extra hydrogen ion, becomes ammonium (NH4), and that is insoluble in water, therefore less likely to be a problem.
Unfortunately, raising the ph of the water can free up the bonded ammonia and cause very quick and effective poisoning, especially with a reading of 8 on the test.
What caused the ph crash? It could have been a lot of things. Check your carbonate hardness of both your pond and tap water. KH has a direct influence on pH. If it's low add some crushed cockle shell to the filter system. Dolomite chips or crushed coral (not coral sand as it will cake) can also be used. If your tap water has a high enough KH and pH, start doing small daily water changes to dilute the ammonia whilst bring the pH back into line.
The filter might need a service. Filters can pump out a lot of acid during the nitrification process. Ammonia, as it is broken down (nitrogen/hydrogen) can produce nitric acid and hydrochloric acid, nitrite can produce nitric acid, and if you had a means of breaking down nitrate, that would also produce nitric acid. A breakdown in filteration may have occurred, maybe a power cut whilst you've been gone.
Also, the bacteria that break down waste do not like acidic conditions. They may have slowed and given rise to poisons that have not been broken down fast enough.
All the decaying organic matter in the pond, in the filter will also produce acid as it breaks down. Any plants in the pond (unlikely with carp) will produce carbon dioxide at night, and take up oxygen. CO2 mixed with water produces carbonic acid. Even the fish will produce acids through excretion and respiration. It's unavoidable.
The recent hot weather would have warmed up the pond and lowered the oxygen content. The fish with the greatest demand for O2 would have perished first, starting off a chain reaction - decaying meat, acidosis, poisoning of environment. The more decaying matter there is, the less oxygen available. Breakdown occurs through the action of bacteria that require large volumes of oxygen. The more there is to break down and feed the bacteria, the more the bacteria breed and consume O2, directly competing with the fish. It is a constant battle for survival.
I'm not saying this did happen, I'm just throwing out theories as to why it could happen.
I would also check the fish for signs of disease. Warm weather and weakened animals is a breeding ground for dormant pathogens. Parasites are the first things to strike, normally. White Spot (easy to see- looks like salt or sugar) and Chilodonella and Costia - harder to see, both produce sliminess of the skin which causes the fish to rub and scratch. Death will occur as the parasites spread to the gills and suffocate the fish. Being a water parasite, they can swim from host to host. Quite deadly in warm weather.

Certainly perform water changes - small and regular (daily 10-15% if your tap water is of a decent hardness and pH), using a good dechlorinator/anti ammonia/chlorine/chloromine product, add a water hardening agent to the filter (dolomite, crushed coral, etc) give the filter a bit of a clean - remember to clean biological media in pond water only to preserve the good bacteria, not under the tap - CHLORINE KILLS!
Adding pure salt can help - slowly reaching a specific gravity of 1.010 (brackish) can help against nitrite poisoning and kill freshwater parasites.
These are all remedies that will work but will take a little time. Abrupt changes can be harmful, especially to a fish in an already weak condition.
Keep feeding to a minimum. Use a wheat germ diet to go easy on digestion and to produce less toxic waste product. (in theory) Also it's coming up for winter - wheatgerm is to be fed anyway during cold weather for the reasons above.

As for other things you have said - all fish are ammonia factories. The biggest fish with the biggest appetites produce the most. Goldfish, carp, minnows, all pollute their environment with waste. The environment needs to cope with that waste or it will collapse, kill the most polluting, until balance is restored and life can continue.
50gallons isn't a lot of water for carp or goldies, to be honest. Carp can grow to 24-36", common goldies can grow up to 12" - and they can live for years (oldest goldfish on record was 42 when it died) provided their environment allows them to do so. At fifty gallons, I would recommend a stocking level of four fully grown goldies - that's approx one inch per gallon, to be on the safe side.
Also, incase of a harsh winter, a minimum pond depth of 24" is recommended. Fish will often retreat to deeper, warmer water when it gets too cold. The deeper the better.
As someone mentioned, too much mixing of the waters through movement may be harmful, so turning off filters might be required. Just keep an eye on those water parameters, especially when the warmer weather returns in spring. Having the filter run independently from the pond, and feeding it with an ammonia source during the winter will allow you to keep it alive and hook up to the pond when the weather improves.
Although, in a pond as shallow as yours, the temperature at various depths will be fairly consistent all through. The wind alone will take care of that.
Good luck. I hope you sort out your problem and manage to save the remaining fish.
 

IronGiant

Moderator
Dave hasn't mentioned a pump or filter yet, he might not have one...
 

HMHB

Distinguished Member
Dave hasn't mentioned a pump or filter yet, he might not have one...

Eek ! If it's a case of having no filter then this build of of Ammonia etc is fully expected, and will get worse as the fish grow.
 
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seafoodmix

Standard Member
i wouldnt run the filter or a pump through winter unless the pond is tiny. The pump circulates the water and all the water becomes colder. If the water is still the bottom of the pond is a little warmer and the fish can be domant down there away from ice and chill.

You can have natural ponds with lots of plants in them and get away with no filter and even not feeding the fish as much cause of natural food but a little pond like daves needs a filter.
 
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HMHB

Distinguished Member
I have always kept my filters running mainly because I don't want to start off in spring with a "toxic filter" or a "new filter". I move the pump to the shallow 4ft end of the pond to take more water from there, but I don't think it really makes much difference where it is.
There's some interesting reading here
 

seafoodmix

Standard Member
true you can keep the bacteria alive in the filter but ive always had problems with freezing water and the plastics getting brittle. there is no need to run a uv though cause algae growth will be dormant with low light and cold water.
 

Dave

Distinguished Member
Sorry for the delay and thanks a lot for the replies, very informative.

As for filter yes I do have one, it's a fishmate thingy with a UV lamp and has functioned fine for over 2 years which is why I'm stumped as to why it's suddenly gone all wrong.

I'll try a water change tomorrow and get a testing kit to keep an eye on things. I have 4 fish left and though they all seem a bit lethargic there's only 1 that is on it's side and not really swimming at all. I've examined the dead ones for signs of disease and can't find any.
 

HMHB

Distinguished Member
I once overfed my fish many years ago in the early days of my fish keeping and a couple of them were on their sides due to high nitrite and ammonia levels. A water change helped sort it out as did using something called envirex which can help to control things.
The problem is that once your fish have suffered high levels of these toxins they can be damaged forever.
 

KoThreads

Well-known Member
As for filter yes I do have one, it's a fishmate thingy with a UV lamp and has functioned fine for over 2 years which is why I'm stumped as to why it's suddenly gone all wrong.

You have changed the UV haven't you, there only good for a year to 18 months.
 

HMHB

Distinguished Member
When was the last time you cleaned your biological filter out?
 

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