The Gulf smooth-hound (Mustelus sinusmexicanus) is a houndshark of the family Triakidae, found on the continental shelves of the tropical western central Atlantic.

[2] This species has a long slender body, a plain grey/brown dorsum, pale/white ventrum and a large and rounded dorsal fin.

The fins have a pale to white trailing margin fading towards adulthood.

The caudal fin is deeply notched; its teeth are flat and pale.

This type of shark can be found in the continental shelf between depths of 36 to 229 m (118 to 751 ft).