Pond Boss Forums STOCKING A NEW POND Creating the food chain New 1/4 acre pond with slow die off of FHM & BG

I have a brand new 1/4 acre, 14' deep pond. After being full for a month or so it had a thriving population of toad tadpoles (and still does) and various frogs.

I stocked w/ 10 lbs FHM, 5 lb GS, 30 LMB fingerlings, 15 HSB fingerlings, 100 BGS fingerlings, 50 HBG fingerlings, 50 RES fingerlings, and 100 Gambusia. I picked up the fish at the hatchery (Jones in Cincinnati) and transporting them took about 60 minutes. I floated the bags for about 20 minutes before releasing them.

For the first few days I didn't notice any fish dying, but after a few days there have been 10 or so dead FHMs every day, then after about a week, 1 or 2 bluegill (not sure which kinds) each day along with the minnows. No mass die offs and so far only 1 dead bass and a couple shiners.

Using a Tetra test strip type test, no nitrites, no nitrates, the water tests hard, but alkalinity is in the normal range and the pH is 8.2. I've had one heavy rain event that blasted the pond with clay mud washed in, but the die offs started before that. Ground water that enters the pond has a similar test profile. However, it is fed primarily by surface runoff from a hay field that hasn't been sprayed.

I have seen a couple bluegills that were starting to show signs, they would swim very slowly close to shore and would not flee from a stick dropped near them. They had a good upright swimming posture and no obvious signs of infections or parasites. Normally I never see any of the fish except the FHMs.

I spoke to the hatchery today and the person I spoke to was perplexed and said she will talk to some of the delivery drivers to get their thoughts.

Any thoughts about what might cause this weird scenario?

Any oak trees in the pond basin?

Some posters have reported die-offs as the tannins leach out of the oak wood.

Not an expert - but in a low oxygen situation, it is usually the larger fish that die off first. I would assume that the opposite would be true for some chemical stress, the smaller fish would have a higher surface-to-mass ratio.

Hope you figure out your problem!

Delayed stress effect. I don't think what you are seeing is really abnormal. It should taper off-I believe..
In a month old pond, the system has just began to build elements that are the beginning of the ecosystem. It takes many parts of the puzzle to balance the system to "be a happy place" for the new arrivals. I think you will see this subside.