Alligator gar (Atractosteus spatula)

The alligator gar (Atractosteus spatula) is a large, ancient fish species known for its long, slender body, long snout, and diamond-shaped scales. It is the largest of the gar species and can grow up to 10 feet long and weigh over 300 pounds, according to the U.S. Fish & Wildlife Service and Texas Parks and Wildlife. The name "spatula" refers to its broad, spoon-like snout. 

Gars are easily distinguished from other freshwater species by their long, slender, cylindrical bodies, long snouts, and diamond-shaped interlocking (ganoid) scales. The tail fin is rounded. Dorsal and anal fins are placed well back on the body and nearly opposite each other.