Look at it closely, it is almost identical to the "freshwatergar" Xenentodon cancila, just a bit bigger and lives in florida, those two clues point to one fish, the common needle fish of south eastern Florida, also called timacu (Strongylura timacu)
Here is one that is freshwater and brackish when young but brackish and saltwater when older. the young ones are shorter through the body, it is often sought as a gamefish.
Nope, here is a hint, reaches a meter, lives in marshes and streams as a youngin, then move to reefs and rocks offshore, Western Atlantic from New Jersey to Brazil.
That was the Horse Eye Jack,(Caranx latus)
This one is about 7" long and often shows up in tanks, it will tolerate FW, full SW, and brackish but in the wild is usually found in Brackish. Pretty and peaceful little guy.