18 dead

[deepwaters]

I have approximately a 4000 gallon pond four feet deep. I live in southeast Pa. Have a powerhead that circulates water to keep about a 2 feet surface area from freezing. In five years I have lost maybe 1 Koi. Last week I lost 16 large koi ranging 12 inches or larger and 1 catfish that was 15 inches and another catfish that was about four inches.My ph is normal and so is my ammonia. I also have goldfish/comets turtles and small Koi in the pond and none of them died, although the fish are by the surface. There was a 2 inch layer of ice on surface at the time of this disaster, but like I said I do have a vent hole at all times. I have not fed them since October. I have not done anything else to this pond differently than other years.

 

[budgenator]

That is a lot of fish for a 4000 gallon pond!

 

[Tula]

Is the vent hole all that you have, no aerator or Pond Breather? It sounds like an oxygen problem to me, given your largest fish died, others are at the surface and your ammonia and PH are normal.

While you may have done everything the same, successfully, for many years.....when our koi grow, so do their O2 needs. Also, if your fish have spawned, you have more fish, in the same sized pond.

I'm very sorry for the loss of your fish

 

[sissy]

sorry to hear but agree sounds like a lack of oxygen and the size and amount of fish

 

[deepwaters]

Thank you all for replying so quickly. Yes I have a powerhead from a fish aquarium that circulates water that prevents it from freezing. No air bubbles. I have done it like this for last four years. I do agree that the symptoms look like a lack of oxygen. If I had a aerator would've that made a difference? Even on the hottest of summer days I've never had a problem with a deficiency in oxygen with even more fish. I would purchase 300 to 400 minnows at a time every two weeks and never have a problem w oxygen. My bass and catfish would feed off them.

 

[Meyer Jordan]

Certainly sounds like a low Dissolved Oxygen issue.

 

[Meyer Jordan]

Thank you all for replying so quickly. Yes I have a powerhead from a fish aquarium that circulates water that prevents it from freezing. No air bubbles. I have done it like this for last four years. I do agree that the symptoms look like a lack of oxygen. If I had a aerator would've that made a difference? Even on the hottest of summer days I've never had a problem with a deficiency in oxygen with even more fish. I would purchase 300 to 400 minnows at a time every two weeks and never have a problem w oxygen. My bass and catfish would feed off them.

What was your total fish load before the mortality incident?

 

[deepwaters]

1 bass 12". 1 channel cat 15" died. 16 koi between 10-15" all died. 1 small channel cat 4" died. 3 three inch painted turtles. Maybe another 10 six inch or less comets. 15 snails.

 

[deepwaters]

If this is oxygen related, how come now and not earlier in the winter when water was warmer and fish were more active?

 

[Meyer Jordan]

When did you take the main pump and biofiltration off-line for the Winter?

Also define normal pH and Ammonia levels.

 

[deepwaters]

I turned off all filtration on thanksgiving. Started power head same day. PH neutral and ammonia clear on test strip. I took water sample to pond store and they tested for both and said both were very good. They also informed me that it's very difficult to test oxygen.

 

[deepwaters]

I like to winterize pond when temperatures are consistently 50 and below.

 

[Meyer Jordan]

I turned off all filtration on thanksgiving. Started power head same day. PH neutral and ammonia clear on test strip. I took water sample to pond store and they tested for both and said both were very good. They also informed me that it's very difficult to test oxygen.

Dissolved Oxygen levels are no harder to test for than any other biochemical water quality parameter. Salifert offers a test kit at a very reasonable price.
http://www.drsfostersmith.com/produ...d=PLA_G_6194&gclid=COO-pq3_x9ECFdm2wAodX9IGhw

With the main pump being off-line and your pond experiencing Ice-over, the water is not being oxygenated as uniformly or completely as during warmer months. Pockets of very low (anoxic) oxygen especially at the deeper levels would be expected. As Tula mentioned, your fish have grown and with this growth has come higher Oxygen demand.

 

[deepwaters]

I will buy that test kit tomorrow. Thank you

 

[DeepWater]

Hello deepwaters welcome , and I am sorry for your losses.