Sphyraena guachancho?
Very wary and difficult to photograph. I chased them for about one minute and they allowed me to get within maybe 10 ft at best a few times.
Snorkeling along the first reef line at Lauderdale-by-the-Sea
My other observations from this snorkeling session:
https://www.inaturalist.org/observations?nelat=26.190688572155167&nelng=-80.07342736156014&on=2021-06-17&place_id=any&subview=map&swlat=26.180098052430257&swlng=-80.1105491317069&user_id=joemdo&verifiable=any
To 8.3 cm long. Large numbers were attracted to a light hung off a dock at night. Hovered off the bottom, probably attracted to zooplankton.
To 253 mm long. Characteristic white spots on first and fifth abdominal segments.
(EN) Threespot squirrelfish - (FR) Poisson-écureuil à taches noires
Sargocentron cornutum, Pura Island, Indonesia