Distribution, abundance, biological traits and growth of Peristedion cataphractum L., 1758 coming from two areas of the Strait of Sicily were analysed. The two investigated areas correspond to the north (A-area) and south (B-area) of the midline located between South Sicily and North Africa. Both published and new elaborated parameters were estimated from data gathered in autumnal experimental bottom trawl surveys; the surveys in the B-area, in particular, were carried out between 1997 and 2004. The abundance resulted to be ten fold higher in the B- than in the A-area. The biological parameters ranges resulted in 0.38-0.48 and 0.42-0.50 (sex ratio), 200-230 and 200-225 mm (median total length of mature stage), 200-232 and 200-222 mm (mean total length of mature stage) and 168-221 and 177-199 mm (size at 50% of sexual maturity) for stocks from A and B areas, respectively. The length frequency distributions were always signifi- cantly different. The von Bertalanffy growth function (derived after sex combined length frequency analysis) revealed a high closeness: 379-390 mm and 0.38-0.36 for L∞ and Ky-1, respectively. These results support the hypothesis of a common genetic-biological features of the population on one side, but also suggest maintaining them operationally distinct (i.e., as “unit stocks” sensu Gulland) since the likely low rate of spatial interchange (as a consequence of the low mobility of this species) and the reported differential in fishing exploitation.