The present invention concerns a box-like fish-trap (1) comprising a frame, which is foldable, involved by a net, characterised in that it consists of: A metallic upper body (2), which floats; A metallic lower body (3); Flexible cables (4) to fix the upper body (2) to the lower body (3); Flexible side nets which connect the lower body (3) to the upper body (2); Frames (6, 7) that hold the nets of the fish entrance openings (5) and which are arranged so as to let the fish come in but make it difficult for it to get out; and One bottom (16) formed by a frame and net fixed in an articulated manner to one of the tops of the lower body and closed at the opposite top, which will make it possible to collect the captured fish.