PROBLEM TO BE SOLVED: To provide a structure that can be easily built up even by one diver in the sea and suitably according to the geographical features etc. of a site and that does not make fish and shellfish alert while being easy for algae and seaweed to grow. SOLUTION: This fish reef block is easy to stabilize even at the bottom of the sea in a horizontally connected state because of having a polygonal base at the bottom face. The fish reef block can be extended stepwise because of having a vertical connecting means at the upper face center of a center protrusion that rises at the center. Each side of the base is provided with a connecting means for connecting the adjacent base, and angular parts between the respective sides, which are pointed in shape and weak in strength, of the base are eliminated. Because the angular parts are eliminated, through-holes for the fish and shellfish to move up and down are formed when a large number of fish reef blocks are horizontally connected. Anchors are further provided for fixing required parts to the bottom of the sea when the fish reef blocks are installed and built up at the bottom of the sea. COPYRIGHT: (C)2013,JPO&INPIT
