The objective of this project was to determine the feasibility of using two-stage anaerobic composting to stabilize crab-picking wastes, produce a residue amenable to byproduct recovery, and to compare flooded versus percolating operation of the leachbed. Crab-picking waste (CPW) was treated using duplicate, two-phase reactor systems consisting of 14-l leachbed reactors and 5-l hybrid sludge-bed filter reactors. Biochemical methane potential of the CPW, solids reduction, methane production and leachate pH, alkalinity, conductivity, volatile organic acids (run 4 only), and chemical oxygen demand were monitored. Methane yields approached or attained the BMP value (0.31 m(3) kg(-1) VS-1), except for run 5 which was stopped at 20 days due to mechanical problems. Mean solids reduction was 80% (SD = 2). Residues were not odoriferous, had a low bulk density (85 g l(-1)) and were stored at ambient temperature with no vector attraction potential. There was no difference in methane yield or VS conversion between percolating and flooded operation of the leachbeds. Copyright (C) 1997 Elsevier Science Ltd.