PURPOSE: To obtain a Cu alloy having superior strength and corrosion resistance and suitable for use as the material of a wire net and a prop for a fish preserve for cultivation by adding specified amounts of Ni, Mn, Al and other element to Cu.

CONSTITUTION: A Cu alloy contg. 5W40% Ni, 0.5W3% Mn and 0.5W3% Al or further contg. ≤3% Fe, Zr, Si, Be, Ti, Sn, Co or Zn is used as a material for a fish preserve placed in sea water. The Cu alloy contg. Ni, Mn and Al is superior to cupronickel (a Cu-Ni alloy) which is considered to be an alloy with the highest corrosion resistance at present in both strength and corrosion resistance, and by adding Fe, Zr, Si, Be, Ti, Sn, Co or Zn, a material for a fish preserve with further enhanced strength and corrosion resistance is obtd.