Lost all my fish in fish pond!!!!

[Catherine]

We have been away camping since Friday morning with our grand daughter and because we are responsible for watering a neighbouring allotment, we have not been able to go too far.

We found our first two fish dead on Friday morning and this morning we found another two fish dead. (They were about 10 years old and quite large about 8 to 10 inches long) There are no markings on the fish so they don't look diseased.

Over night on Thursday/Friday we had to switch off the waterfall as the filter needed changing so we thought it might have been a lack of oxygen in the water, but the two this morning had the water filter and bubble maker on all night so that was not the case today.

Any ideas please because we need to replace the fish into this pond and dont want to introduce new fish, which are quite expensive, to a dodgy pond. (We have had this pond for many years and have never had this problem before)

[Primrose]

We don't have fish in our mini pond Catherine but I do know other people who do, and my first thought, if it wasn't disease, could be lack of oxygen, which whilst it may not have affected the two other fish immediately, could have had a delayed effect.
Not sure where you're living (in the north I believe) and wonder whether the water temperature could suddenly have warmed up and affected them, or possibly a sudden build-up of algae?
Assume you haven't been putting something like Weed & Feed on your lawn which could have seeped into the water, or been spraying plants nearby with some kind of insecticide or herbicide which could have contaminated the water.

It seems strange they should all die about the same time. Would it be possible to consider changing the water in the pond before replacing the fish?

[the custodian]

ive benn keeping fish for about 20 years now, have you done a ph test on the water and tested all nitrates etc i would certainly do a 50% water change, what size is the pond approx and what type of fish are you keeping any plants etc, all info will help me to understand whats happening.

i used to keep koi some up to about 4ft in only my second year somebody for the park behind decided to through a small bottle of bleach into the pond and i lost all but 1 some off them cost me hundreds due to being show fish, onlt thing to do then was empty everything scrub it and the filters and start again

please let me know if i can help with info

[PLUMPUDDING]

I'd guess at lack of oxygen it seems to affect the larger ones first, and perhaps the other two didn't succumb as quickly. I've extended the time my pump is on while it has been hot and put it on full time if the hot weather lasts a few days.

A couple of years ago we had a power cut which caused the circuit breaker to cut out and I didn't know the pump was still off and I lost all my large golden orfe and goldfish, but the smaller ones were all OK and are now nice big fat ones.

[Catherine]

Today we spent most of the afternoon (after being rained off our camping weekend with torrential rain and high winds) emptying our pond, only to find three more fish at the bottom of the pond. We don't know why the others died and these didn't but they are now in a large trug with a bubble maker whilst we empty the pond, clean and fill with more water. Then we will fill with clean water and leave for 24 hours and then put these three lucky fish back into a pristine pond.

I don't know what we did wrong, we half emptied it three weeks ago and put clean water in, and we were going to do it again this weekend. Our pond's pump does not run through the winter but we do run a bubble maker all the time. We have three filters which we change on a regular basis but we did not run the pump or the bubble maker on Friday night when it had been very sunny all day and warm in the evening.

Today we found the fifth dead fish when we went to empty the pond.

We will put the three lucky fish back in tomorrow. Watch this space.

[Primrose]

One other thought which occured to me, and it's probably way out, is that when you mentioned half emptied and refilled your pond recently, did you fill it with water from a hose straight from a tap?

Every so often the amount of fluoride or other chemical agents which local water authorities put into the system to keep the water hygienic may temporarily & briefly have exceeded normal permitted levels. Because of the hot weather, the level of concentration might have been higher than normal to prevent harmful bacteria levels rising. Whilst this might cause no ill effect to humans, fish being much more sensitive, could be badly affected.

Might be worth contacting your local water authority to see if any blips have occurred.

[Catherine]

Yes we did fill it from the hose pipe from the house so maybe that could have been the reason. Our pond was pretty green so we dont think the pump had been working properly, now we can see down to the bottom and the three lucky fish are going back in any minute. Then netted to stop the heron having breakfast. Do fish have nine lives Maybe they have used up their first one this weekend.

[Primrose]

Catherine
Bright sunlight is one of the key things which causes green algae in ponds. We have a little 'sink pond' located in a very shady part of the garden. It develops far less algae than our other mini pond which gets more sunlight and in which many of our tadpoles seem either to have died or disappeared. I don't know if there's any connection but most of tadpoles in the shadier sink pond are still there in the same numbers. So possibly the algae develops to dangerous levels for the wildlife in the pond and kills it off. I'm now covering over part of the sunnier pond on bright sunny days to hopefully reduce the amount of algae which forms.

[the custodian]

you could try putting a uv filter on your system as when the algea particles pass through the uv light it kills them off thus reducing the green, also on a hot sunny day i would deffinately have my pumps running as when the water heats up any plants that you have in your pond will use up the residue oxygen in the water leaving you with a stagnant pond and unhappy fish

[Catherine]

Thanks TC we have a UV filter on the pump and we have now replaced it today, and bought three more fish. 3 Golden Orfe £13.00 just imagine what the ones we lost over the weekend would cost They seem to have settled in nicely, so we shall have to see how things go. Many thanks for all your suggestions and advice. I will keep you updated. (Not quite as exciting as the fox topic) That I find facinating to have a wild animal in the garden. I love foxes.

[Monika]

Sorry to hear about your fish, Catherine, and I hope the new ones will be happy and healthy!

If you ever have to fill the pond again straight from the tap, one tip: if you spray the water finely through the air into the pond on a sunny day, the chlorine will be dispersed in the sunshine before the water hits the pond.

Also, if you introduce some duckweed to the pond, this will shade out the light. Unfortunately, you may have to scoop it out every so often to reduce it.

[Catherine]

Thanks Monika, we are hoping that we dont have to do this again. The fish seem very happy tonight but are not eating the fish food we put in there, although only a small amount so we will keep an eye on them over the next few days and hopefully they will be okay. At least now we can see them swimming round the pond.