Tracy, about to hit the road, so I'll add to this later today. My thoughts have changed about hatchery ponds, so think more along the lines of a shoe box, not a paint roller pan. The gradual incline at the removal end of the pond gets extremely silty once that net drags through it. That's very rough on the small fish since their gills get filled with silt unless you pull them out post haste.
As far as size, determine the size of the net you're comfortable working with, then base the width of the forage pond on that net. The smaller the the netting mesh size, the harder it is to pull. 1/4" to 1/2' nets are much harder to pull than 3/4' to 1' nets.
