Koi and goldfish from a garden pond

Asked January 27, 2020, 9:26 PM EST

We have a small pond in our back patio. There are several adult koi a nd goldfish and about 20 babies from last summer. This afternoon I intended to clean the pump and when I brought it up I noticed 4 babies have recently died. 2 kois and 2 fan tailed goldfish. Is it possible to have them examined to find out the cause of death ? Two other babies have died early December.

Howard County Maryland

1 Response

Depending on whether the pond is above-ground or sunken, temperatures may have played a role in stressing (or killing) the fish. In-ground ponds are more insulated and less prone to drastic or rapid temperature swings. Is there a de-icer being used to keep some of the water surface thawed to allow for gas exchange?

If you haven't already, check the water chemistry to make sure conditions have not turned anoxic or otherwise imbalanced. You might inquire with local independent fish stores (as opposed to larger pet chains) to ask if they can do any testing or have any experience in causes of outdoor fish mortality.