I've never done it, Rocmon, but I have read that you can cut the open-end off of a soda bottle, and then stick it back into the bottle, and put some food in the bottle... then put the bottle in the pond, fill with pond water, and let it float. Supposedly the fish will swim in after the food and have a hard time finding their way out.
YOur minnows would probably swim in too, but you could always put them back in the pond.