Soil amendments and fertilizers may include potentially toxic elements that may be accumulated by plants. The elemental composition of municipal sludges has been studied in great detail (Furr et al. 1976; Mumma et al. 1984). Fish hatcheries in south-central Idaho have been ordered by the U.S. Environmental Protection Agency to discontinue sweeping accumulated wastes downstream into the Snake River. Alternatives include landfilling and domestic use of the manures as lawn fertilizer. It has been proposed (Smith, 1982, 1985) that fish manures are suitable fertilizers for crops such as corn and sugar beets. Sewage sludges and manures have increasingly been disposed of as soil conditioners and low grade fertilizers. In 1981 the U.S. Environmental Protection Agency proposed upper limits of certain heavy metals for sewage sludges suitable for land application. The following upper limits (ppm) were proposed: cadmium (25), chromium (1000), copper (1000), lead (1000), mercury (10), nickel (200), and zinc (2500). We determined the concentrations of these elements, plus arsenic and cobalt, in fish manures being evaluated as fertilizers for Idaho croplands. We also determined nitrogen, phosphorus, and potassium in fresh fish manures.