a fish protection system for dams comprises a series of modular units which interconnect by male and female fittings on each side of the modular unit . each modular unit comprises a casing , an inner box and an outer box for anchoring the unit to a stream bed and side frames . a screen and cleaning mechanism can be placed within the modular units where the screens clean and direct debris and fish to a fish ladder . a cleaning comb or cutting bar moves around the modular unit such that it keeps the screens clean and directs the debris and fish to the fish ladders . the cleaning comb by use of its rounded tooth form , minimizes flow at the screen in order that fingerlings won &# 39 ; t be harmed by the cutting edge . a fish ladder provides a constant flow by maintaining the same depth of water by a hinged ladder .