Bass (fish), Basse, the popular name or any fish of the genus Labrax, of the family Percidae, distinguished from the true perches by the opercular bones being covered with scales, the spines on the operculum, and by the minute closely-set teeth on the tongue. They have two dorsal fins, the first with nine spines; the anal generally with three. Bass are common on the European and Atlantic coasts, and in the fresh waters of America. There are three European species, almost exclusively marine, of which the best known is Labrax lupus, the common bass, sea-dace, or white salmon - known to the Greeks by its generic, and to the Romans by its specific, name. It is generally from twelve to eighteen inches long, though much larger specimens are fairly common. In form it resembles the perch; upper parts dusky blue, passing into silvery white on the sides and belly, fins pale brown. It is an extremely voracious fish, and was formerly in high repute for the table, though now it is little esteemed. It is more abundant on the south coasts of England and Ireland than farther north, and ranges to France, Portugal, and the Mediterranean. L. lineatus, the rock-fish or striped bass of North America, closely resembles the common bass, but is somewhat larger, and marked by seven or eight longitudinal black lines on a silvery ground-tint.