Mechanical harvesting of the submersed weed hydrilla, Hydrilla verticillata (L.F.) Royle, in Orange Lake, Florida entangled fish in the cut vegetation resulting in their disposal with the weeds on shore. Three block-net samples in dense hydrilla indicated fish standing crops (mean ± SD) of 205,000 ± 35,000 fish/hectare and 460 ± 30 kg/hectare. The estimated loss of fish to mechanical harvesting represented 32% of fish numbers and 18% of fish biomass. Fish most susceptible to mechanical removal with hydrilla were juvenile sportfish and smaller species. The monetary replacement value of the fish lost was estimated at over $6,000/hectare.