5' deep pond is shallow is it spring fed?
Can you aerate it to keep it from freezing that would be the issue I could see because once it freezes over O2 level would be depleted killing off the minnows they should withstand the cold just won't live without oxygen
Remember when posting what may seem innocent to you may not to others,
text shows NO emotions so please,,, don't take it personal & automatically go on the defense.
Take it w/ a grain of salt, take it as a joke or just let it go.
"If George Washington was asked for his I.D. do you think he just wipped out a quarter?"