A ballast weight for a fishing line, comprising a main body (1) destined to be associated to a fishing line, which comprises a through-channel (10) provided with an inlet opening (11) and an outlet opening (12) located on the external surface of the main body (1), said through-channel (10) being overall orientated in a parallel direction to a longitudinal axis (x) of the main body (1) and being provided with a progression and a breadth that are variable.