This
http://www.theaquariumwiki.com/Lepisosteus_oculatus says:
Identification
An elongate slender fish with a long pointed snout and dorsal fin set way back towards the rounded caudal fin. The flanks and fins of this fish have large brown spots on a silver base colour.
This species of gar rarely exceeds 91cm (35.8"), and the average length is 76cm (29.9"). Its body is cylindrical and often mistaken for a log lying in shallow waters. This gar is covered with hard, diamond-shaped ganoid scales. Their bodies are spotted, including the top of the head and the fins.
Lepisosteus oculatus is often mistaken for the Florida gar, Lepisosteus platyrhincus; the two can be distinguished by the distance from the eye to the gill cover. In the spotted gar, this distance is greater than two-thirds the snout length, while this distance in the Florida gar is less than two-thirds.
Bold underlined is mine. IIRC though, these gars are hybridized by people and they too hybridize in the wild as their native ranges / areas overlap. IDK how prevalent the hybrids are.
I have a similar problem - I bought a (nominally) spotted gar from Shark Aquarium about half a year ago. It's about 10" now. I've been lazy to get a good photo of the head to do the measurement.