I've also seen fry during the winter here in Western PA.

I couldn't really tell what species they were though. In one particular virgin pond that was just stocked with 27 adult bluegill in August of 2021, along with maybe 100 fathead minnows, I could see very small fry in January '22. So it was either fatheads or bluegill.


Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."