The technique The basic design involves a gutted refrigerator or better yet a freezer. The box is prepared by adding an inlet with aeration and a discharge. The inside of the box has a series of plexiglass plates placed vertically to channel the flow through up to 18 Witlock Vibert Boxes (WVB’s). The WVB, yes Dave WHITLOCK had a part in the design, has two chambers. The smaller top chamber holds up to 500 eggs. Typically, about 90% hatch and drop into the larger lower chamber through slots large enough to accommodate the fry and yolk sack. There they stay until they absorb enough of the sack to fit through the smaller slots and into the main refrigerator chamber. While still in the refrigerator they are safe from predation until lage enough to swim to the surface. At this time they will be sucked out the out flow and flushed into the stream where they will have to survive on their own. (see photos below)