English: A schematic of a small scale fish hatchery, together with a baffle box. This setup could be very useful to repopulate a river with (certain) remaining fish species in that river (ie after loss of fish due to environmentally damaging industrial activities). The fish spawned in the hatchery would need to be placed in the river as fast as possible (due to the little space, they would otherwise die quickly). The schematic was made based on a schematic seen in episode 3 of "Edwardian Farm" (http://www.bbc.co.uk/pressoffice/pressreleases/stories/2010/10_october/14/edwardian_farm3.shtml ), and after studying http://www.lakelandgov.net/publicworks/lakes/lhwrstp.html , http://ag.arizona.edu/azaqua/extension/BMPs/Final_EPA.html (Recirculating Trout Farm Design) The boxes are made of wood, and are made waterproof by means of pitch (pine resin). The water coming in would need have been well aerated first (ie by waterfalls). Also the boxes would typically above the water (they shouldn't be submerged, ...); instead they are simply placed between a river (watersource) and a lake, ...