Well mine ranged from the size you see in the pic to some that were 3-4 inches. They grow fast so I am sure these were the smaller one.

I have some in my pond pushing 2 pounds now but of course they do not want to bite.

I usually throw them back but since I do not make it to the pond that and wanted some fish for dinner I kept these. Plus there are many more in the pond still.

Not sure of the winter tilapia you mention, there are the Blue Tilapia that are the most cold tolerant but they still die in the winter, and are fine in the summer as well.

I would like to know more of these you talk about and what type they are.

Thanks