Fish dying for no apparent reason

[TetburySue]

In the last 48 hours, three of our pond goldfish have died. They don't appear to have anything wrong with them externally (we checked them over thoroughly and can't see any signs of disease of infection). The pond water is testing OK for everything (using a dip test and comparing the results to the index on the package). The pond is not large but is well established and until now the fish have been very happy. We have a pond pump and two air stones so there should be enough oxygen for the number of fish, which has been constant for a long time (we haven't added any new ones - the fish we have are all offspring of the original four we bought six years ago). Tomorrow I am planning to do a complete water change and give the pond a good clean in case there is some pathogen in the water that we are unaware of. I would welcome any thoughts or advice as to why this is happening and more importantly what we can do to protect the approximately 12 fish we have left. I have got some tap water additive and will be putting that in when we refill the pond. If you think we should be adding anything else please let me know. Thank you.

 

[GBBUDD]

Tomorrow I am planning to do a complete water change and give the pond a good clean in case there is some pathogen in the water that we are unaware of.

Not the plan of attack i would take. Drainingvwill only remove the water and LESSON the concentration if it is flukes or some other parasite. Id treat the water then do good water changes. And cleaning will again lesson ypur consentrations like muck but also the bacteria that has taken years to grow and get ballanced . That is if your pond is in good shape.
Test your ph kh make sure your adding your dechlorinator if you use city water

 

[TetburySue]

Not the plan of attack i would take. Drainingvwill only remove the water and LESSON the concentration if it is flukes or some other parasite. Id treat the water then do good water changes. And cleaning will again lesson ypur consentrations like muck but also the bacteria that has taken years to grow and get ballanced . That is if your pond is in good shape.
Test your ph kh make sure your adding your dechlorinator if you use city water

Thanks for the advice. We have changed out minds about a complete clean out and will be doing a partial water change instead. I'm heading to the aquatic centre in a short while to see if I can buy something to treat the water in case its parasites, but I actually think it may be oxygen levels. It has been a long hot summer here in the UK and we are now getting a lot of rain. I understand this change can cause issues with the oxygen in the pond. We may have to add more bubble makers - we already have two, and a decent pump but perhaps we need more. At least no more fish have died overnight so that's a relief! I'm just really sad because I've lost Tracey, who was my favourite and one of the original four I bought 6 years ago. :-( S/he was enormous! Weighed over half a kilo!).

 

[GBBUDD]

You mentioned a lot of rain have you tested your PH ? Below 7 is time to act and act fast. Regardless of your ph number adding baking soda will help raise it. That and the kh which is key to fish keeping as its a buffer to keeping the water soft and not acidic which is below 6.5. Ph that is 7 to 7.5 is ideal but going higher is fine.. some plants and inverts dont do as well with ph up at 8.3 but when you add anything to your pond do it slowly. Get a kh test kit and you realy want to be up at a 100 to 140.

 

[TetburySue]

You mentioned a lot of rain have you tested your PH ? Below 7 is time to act and act fast. Regardless of your ph number adding baking soda will help raise it. That and the kh which is key to fish keeping as its a buffer to keeping the water soft and not acidic which is below 6.5. Ph that is 7 to 7.5 is ideal but going higher is fine.. some plants and inverts dont do as well with ph up at 8.3 but when you add anything to your pond do it slowly. Get a kh test kit and you realy want to be up at a 100 to 140.

The PH was fine - we did check that. I've done a partial water change and added stuff to make the tap water ok for them, so I'm hoping that will work. The people at my local acquatic centre think it might just be down to temperature change as it's gone from very hot in recent weeks to much cooler and wetter, but they didn't really know what to suggest beyond doing a water change. When I was doing that I found another dead fish at the bottom of the pond, so that's four in three days. Very sad. I really hope I've solved the problem now as I don't want any more to die. :-( I shall just have to wait, cross my fingers and see what happens next.

 

[j.w]

The PH was fine - we did check that. I've done a partial water change and added stuff to make the tap water ok for them, so I'm hoping that will work. The people at my local acquatic centre think it might just be down to temperature change as it's gone from very hot in recent weeks to much cooler and wetter, but they didn't really know what to suggest beyond doing a water change. When I was doing that I found another dead fish at the bottom of the pond, so that's four in three days. Very sad. I really hope I've solved the problem now as I don't want any more to die. :-( I shall just have to wait, cross my fingers and see what happens next.

If you do anymore water changes make sure to run the new water in very slowly so there is less shock to the fish due to change in water quality and temperature. Sounds like possibly your fish have grown a lot and they will be creating a lot more build up of nutrients in your water. Perhaps a bigger filter is needed? Extra aeration can't hurt either. If it's parasites or ? that's a whole other issue.

 

[GBBUDD]

Smaller ponds in direct sun light can have dangerous temp changes. Shad in the morning and then direct sun at noon can heat the water quickly. Thus is why smaller ponds are harder to keep than larger.

Do you see your fish rubbing against the sudes or botto. Of the pond ?

 

[WaterGardener]

There is always a reason. Sometimes it's difficult to identify it. I'm sorry you are losing fish and I hope you can find and correct the cause.

Those test strips are not very accurate. The liquid tests are better. I would recommend that you get those and test your water again. Be sure to get a KH test. To me, it is one of the most significant things to keep track of in your pond.

Best of luck to you.

 

[GBBUDD]

Be sure to get a KH test. To me, it is one of the most significant things to keep track of in your pond

Agreed , and unfortunately the last fish keeper learn of and or test for
Its a crime that api test kits dont have kh in there kits. But they sell way more of there kits to aquariums than they do to ponds so i get it.
Theres not much acid rain falling in an aquarium. Acid rain in ponds is the silent killer.

 

[Lisak1]

The most common thing we hear when there are pond issues is "everything has been fine... until now". What's the one factor that continually changes - the size/quantity of fish in the pond.

Sounds like you had about 15 fish to start with - how big is your pond? What kind of fish do you have? There's a world of difference between 15 goldfish and 15 koi for example. Has anything changed recently - any new fish added, new chemical, work happening around the pond, etc. RARELY is the cause external. Parasites are possible but generally happen with new fish added to an existing population. Oxygen depletion sounds far more likely. Which fish are dying - the larger ones?