The authors agree that this surname derives from medieval nicknames based on the term pesce ('fish'), with diverse motivations: the most frequent points back to the trade of fisherman or fishmonger, although physical or behavioural characteristics of the original bearer may also come into play.

F. Miranda adds a symbolic dimension: in the Christian tradition, the fish represents the good believer and even Christ himself, linked to the image of the fisher of souls. The Greek term ICHTHYS functions as an acrostic of Iesous Christòs Theou Yiòs, Sotèr ('Jesus Christ, Son of God, Saviour'), so it is not ruled out that some lines adopted this name with that religious sense. E. Rossoni documents the transformation into a surname in Liguria from the 17th century.

The surname has independent origins in different regions of Italy. E. De Felice and P. Regati note a very high frequency in Liguria, a region where Péscio is specific. Rossoni specifies the distribution of the variants: Pesci is proper to the centre-north; Pescini, to the Florence area; Pescione, to Avella, in the Avellino area (Campania); Pesciolini and Pescioni, to Florence and Prato respectively; Pesciotti, to Rome. Miranda adds an extended presence in Veneto, Piedmont, Apulia, Lombardy and Calabria.