text: All of the answers prior to mine are possibly right  can you provide any more info i.e. did it make a drumming sound ,does the edge of the caudal fin (tail) have a blue tint as does a small red fish the size you described?longnose gar in there juvenile state which would be the size you described could possibly have only one spot, but the long nose should have been a give away. I think you caught a red drum though.         P.S.Spottail is strictly saltwater fish they require very high salinity to  for comfort.....P.S.S.We also have a species of bream in the Apalachicola and choctawahachee river systems called painted bream which have many different colors as well as patterns. Most spots are dark red almost maroon, but I have seen them w/ black spots....