The fish you thought was a Tilapia is a Black Acara. They are all over South Florida. Also Called a Port Cichlid or Cichlasoma Bimaculatum
Mayans in South Florida are a pest, they are everywhere, all you have to do is go to any canal and 90% of your hits will be Mayans.
The people who think they see convicts are mostly confused: Juvenile Tilapia Mariea change their patterns in seconds, and show 9 vertical stripes most of the time. In the water they look Black and white, but they are greenish in the aquarium.
Oscars are the easiest fish in the world to catch: Throw a hook with a dead fish in front of them and they will hit it. Same with Jaguars. These fish are not even rare anymore down here.
I have caught:
Jaguars, Red Devils (Labiatum), Midas (Citrinellum and Zoliosis), Texas, Acaras, Oscars (Wild and Albino), Bullhead Cats, Walking cats, Armored Cats, Cichla (hundreds), Blue Tilapia, Spotted Tilapia, Freshwater Eels, Mollies, Pike Killifish, Mayans (thousands, really).
My all time favorite catch: