The weakfish Cynoscion regalis is a fish of the drum family Sciaenidae.

The head and back of this fish is of dark brown color, with a greenish tinge. The sides are of a faint silvery hue, with dusky specks, and the belly is white. The common name of this fish seems to have originated based on the weakness of the muscles in the mouth which often cause a hook to tear free, allowing the fish to escape. It grows to 3 feet (1 m) in length and 19 pounds, 2 ounces (8.67 kg) in weight. The range is from Nova Scotia, Canada to northern Florida. It is fished both commercially and recreationally.

Due to its unappealing name, some retailers have begun to refer to weakfish as "sea trout", although this fish is not a trout by any means.

Also see Sciaenidae