Only if permitted.
Fresh fish: all those species provided with fins and scales. As it is impossible to list them all, here are the most common species: trout, hake, cod, sole, seabass, sea bream, sardine, pilchard, sardone, anchovy, tunafish, mackerel, mullet, surmullet, red snapper, grouper, carp, herring, pike, perch, sand steenbras, red mullet, flounder, John Dory, salmon, gleans, brill (not turbot), plaice.
Important: to note that the statement of the fishmonger is not necessarily correct. Do not purchase skinless fish, in order to verify that the fish has scales (fins come with scales, but not viceversa). Moreover, always ask the fishmonger to wash the knife and the working bench before working for us.