Weakfish Cynoscion regalis and striped cusk-eels Ophidion marginatum both produce sounds, but there has been confusion in the literature on a particular sound, the “chatter.” It has been stated that this sound is produced by weakfish using their pharyngeal teeth. Striped cusk-eels make a similar sound (but not identified in the literature as a chatter) using sonic muscles associated with the swim bladder and vertebral components. The striped cusk-eel identifications were based on captive fish sound recordings, whereas the weakfish identifications were based on recordings made in situ where weakfish were visually observed but other sound-producing organisms could have been present. Based on new signal analysis of striped cusk-eel sounds made in captivity, we identify that species as the source of the chatter sound in our field recordings. The dominant frequency of the sounds increased while the pulse period decreased over the temperature range 18.0–27.5 C. The acoustic characteristics presented here will aid researchers in their identification of these sounds.