The weight for lines of the long-line bottom (coarse) or pelagian type includes a ballast (19) with automatic filling controlled by a vent (20) for producing a slow immersion of the main line in a position held close to horizontal. This weight has a density close to 1 at the moment of its immersion and it is in the form of an inverted cylindrical flask or the like (9) equipped, at its neck (15) with a lead roundel (14) locked into the said neck (15). This weight includes a quick fastener (21) for easy anchoring to the line. <IMAGE>
