Goldfish Sudden deaths

[UK Sub]

Hi Chaps
I was hoping for some emergency help!
I have a medium/large garden pond, about 8000 us gallons, stocked with a few Koy (6 between 10" to 24") many Comets and 7 Channel Catfish (all a bit over 24")... The main pond is being fed from 2 300 gal stock tanks feeding into a stream which drops into the main pond. I have an Ultima II filter running at 7500 gph. Pond has been up and running for about 9 years with no issues up to now.
I have had 3 of my large 6"ish Comets die in the last 3ish days, all of them in one of the 300 gal stock tanks. They do not show any signs of illness/parasites, I just found 2 dead (probably been dead a couple of days, didn't look fresh) and 1 almost dead, I euthanized him.
I am a bit concerned, to put it mildly!
I have no idea what to do for the best. I ran the filter backflush, and have started adding fresh well water, I was intending to do a major water change. That is the only thing I can think to do that might help.
Can anyone help with some advice/ideas?
As far as I can see, all the fish in the main pond are fine at the moment, all eating ok and not showing any sings of distress/illness.
Any help/ideas would be gratefully received.
TIA
Jon Tribe
Maryland US

 

[GBBUDD]

7 channel cat fish all over 24 inch is a good fish load add in a few koi in the same neighborhood an MANY comments you may have reached the tipping point. But it's usually the koi that go first and the biggest.

You never mentioned what your doing to aerate the pond.

I would start rehoming some of those cats and drop the many comments to 50 or less .
Stress coat is a great product for stressed out fish adding a lot to the pond could help anyone else that is stressed out.

Have you tested your water.? Everything looks ok ?

I'm not aware of the filters you folks use on the other side of the pond but many of them seem a bit outdated. Is a upgrade needed?

 

[JRS]

Sorry to hear about your problems. In addition to the points above, no new livestock-fish or plants recently introduced? Doing the trickle water change with your well is a good idea, unless testing shows a larger one immediately necessary. Do you have lots of plants or do regular water changes? Thinking high nitrates which can cause issues, if the more obvious ammonia/nitrite are ok.

 

[UK Sub]

7 channel cat fish all over 24 inch is a good fish load add in a few koi in the same neighborhood an MANY comments you may have reached the tipping point. But it's usually the koi that go first and the biggest.

You never mentioned what your doing to aerate the pond.

I would start rehoming some of those cats and drop the many comments to 50 or less .
Stress coat is a great product for stressed out fish adding a lot to the pond could help anyone else that is stressed out.

Have you tested your water.? Everything looks ok ?

I'm not aware of the filters you folks use on the other side of the pond but many of them seem a bit outdated. Is a upgrade needed?

Hi GBBUDD
Thanks for the input.
Water test seems all ok, zero ammonia, Nitrite, pH is at about 7.6
My aeration is taken care of by the 2 small waterfalls from the stock tanks plus a have a bubbler.
My filter is an Aqua Ultima II bead filter rated for up to 20,000 gal so, hoping that is OK for my setup.
I have not added any salt to my pond yet this year, I normally add 80 - 100 lbs, I will add some this week.
BTW, I'm originally from 'other side of the pond' but right now me and my pond are just outside Baltimore MD.

 

[UK Sub]

Sorry to hear about your problems. In addition to the points above, no new livestock-fish or plants recently introduced? Doing the trickle water change with your well is a good idea, unless testing shows a larger one immediately necessary. Do you have lots of plants or do regular water changes? Thinking high nitrates which can cause issues, if the more obvious ammonia/nitrite are ok.

Hi JRS
I have minimal plants, no new additions to the pond either. I do fairly regular water changes when I run the backflush feature on the filter. My water test didn't show anything worrying zero ammonia, Nitrite, pH is at about 7.6

 

[WaterGardener]

Salt is no longer recommended for fresh water fish ponds. Years ago it was the norm, but not anymore.

It does sound like you could be overstocked. Filtration systems are generally rated at twice or even 3 times what they can actually handle, so your 20,000 gallon filter is really only good for 10,000 at best. And with that fish load, you have likely exceeded it's capacity.

It's not unusual for ponds to do well for years, then have problems. That is often because those once small fish have now become huge, creating an enormous amount more waste than they did before.

Do you have a KH test kit? Have you tested the KH? It's possible that with all the recent rains in this area, your KH has been depleted and your pH is bouncing around or crashing.

 

[mrsclem]

My question is why these fish were in a 300 gallon stock tank and not in the main pond. Can you post pictures of your setup? Are all your fish in the 2 stock tanks or are they in the main pond?

 

[GBBUDD]

Hi GBBUDD
Thanks for the input.
Water test seems all ok, zero ammonia, Nitrite, pH is at about 7.6
My aeration is taken care of by the 2 small waterfalls from the stock tanks plus a have a bubbler.
My filter is an Aqua Ultima II bead filter rated for up to 20,000 gal so, hoping that is OK for my setup.
I have not added any salt to my pond yet this year, I normally add 80 - 100 lbs, I will add some this week.
BTW, I'm originally from 'other side of the pond' but right now me and my pond are just outside Baltimore MD.

ah i do know your filter that and a bakki shower are a team that can't be beat. Not a salt guy myself

 

[UK Sub]

My question is why these fish were in a 300 gallon stock tank and not in the main pond. Can you post pictures of your setup? Are all your fish in the 2 stock tanks or are they in the main pond?

I'll post some pics tomorrow. The 2 stock tanks have some Comets, just really because it looks nice. They are set up with rocks and Iris.

 

[UK Sub]

Salt is no longer recommended for fresh water fish ponds. Years ago it was the norm, but not anymore.

It does sound like you could be overstocked. Filtration systems are generally rated at twice or even 3 times what they can actually handle, so your 20,000 gallon filter is really only good for 10,000 at best. And with that fish load, you have likely exceeded it's capacity.

It's not unusual for ponds to do well for years, then have problems. That is often because those once small fish have now become huge, creating an enormous amount more waste than they did before.

Do you have a KH test kit? Have you tested the KH? It's possible that with all the recent rains in this area, your KH has been depleted and your pH is bouncing around or crashing.

Thanks WaterGardener, my pond volume is a bit tricky as it's not a regular rectangle and has variable depths, but as best I can guess it's probably about 9000 gals, so my Ultima should be ok I would hope, the fish load is quite high though, all the catfish are at least 2ft and 2 of the koi are 2ft.
I don't have a KH kit, I'll get one.
If I'm suffering filter capacity issues, would I be getting ammonia spikes? I'm currently not getting any ammonia issues

 

[WaterGardener]

It does seem that your water quality would be having issues with that many large fish. But you are correct that the tests aren't showing that.

Are your test results from the 300 gallon ponds or just the main one? Are you testing each one separately?

My pond has a bead type filter like yours, rated at over 4 times the volume of the pond. And there is also a shower filter for even more filtration. I'm a firm believer that there is no such thing as too much filtration.