Thank you for the responses. I am going with Bill Cody's knowledge - they most probably are bluntnose. They are not bullhead (cat) fry - these are true minnows. I went to the Wisconsin Fish ID site (thanks ewest) and looked at the examples there. These minnows have what appears to me to be a more triangular snout than the bluntnose shown, but it is awful hard to tell the fish are so small. I did not use a magnifying glass and my eyesight ain't what ist used to be.
I am more concerned about viruses, etc. And now I feel bad - I have been adding crawfish that I trapped in the creek to the ponds. No doubt there is a risk there as well. I even dumped in a bucket of creek water. Guess I won't do that again.
I probably won't ever drain the pond as it takes to long to fill - not much runoff, and it is an emabankment pond. I would more likely live with the problems that come in from the wild. I am guessing it is not a matter of if, but when the contamination occurs.

There is a small creek within 20 feet of the big pond, and the small pond that has been there for 25 years is 15 feet away. The blue heron and canada geese have already visited as well as the turtles and crawfish that are now resident.

I did see a lot of small sunfish that appear to be GSF in the minnnow traps, along with some catfish fry. Hopefully these won't hitch a ride into my waters anytime soon.

2/3 acre pond 12 miles from that big pond we call Lake Erie.