Tall tote and cut a 10" diameter round hole in the top of the lid (for entry and exit). It's the only thing we have been able to come up with due to the same problem you have. And it's worked now for several years.
A single electric at the top looks good and won't harm anything. Lesson will be learned quickly by anything trying to cross it. Probably the cheapest method for a long distance.
16" wide sheet of "plastic corrugated roofing" (think greenhouse)....Fastened to the fence horizontally at the top all...
As long as the minnows haven't been cooked, I don't see the problem. We have a cat that makes it almost impossible to fillet fish.
I give her the 1st fillet to keep her busy while I continue. She goes through bones and all. Never a problem.