The white croaker is the only species of in the genus Genyonemus. Other common names for the fish include Pasadena trout, tommy croaker, and little bass.
The body of the white croaker is elongate and somewhat compressed. The head is oblong and bluntly rounded, with a mouth that is somewhat underneath the head. The color is incandescent brownish to yellowish on the back becoming silvery below. The fins are yellow to white. The white croaker is one of five California croakers that have mouths located under their heads (subterminal). They can be distinguished from the California corbina and yellowfin croaker by the absence of a single fleshy projection, or barbel, at the tip of the lower jaw. The 12 to 15 spines in the first dorsal fin serve to distinguish white croakers from all the other croakers with sub- terminal mouths, since none of these has more than 11 spines in this fin.
White croakers eat a variety of fishes, squid, shrimp, octopus, worms, small crabs, clams and other items, either living or dead. While the ages of white croakers have not been determined conclusively, it is thought that some live as long as 15 or more years. Some spawn for the first time when they are between 2 and 3 years old. At this age they are only 12 to 15 cm (5 to 6 inches) long and weigh less than 45 gram (0.10 pounds). The largest recorded specimen was 41.4 cm (16.3 inches), no weight recorded; however, a 36.8 cm (14.5 inch) white croaker weighted 640 gram (1.41 pounds).