Alligator Gar

The Alligator Gar is one of the largest freshwater fish native to North America, belonging to the ancient gar family Lepisosteidae, a lineage that has existed largely unchanged for tens of millions of years. It is named for its broad, alligator-like snout and double row of sharp teeth in the upper jaw. Found primarily in the lower Mississippi River basin and Gulf Coast drainages of the southeastern and south-central United States, extending into Mexico, it can grow to well over two meters in length. Like other gars, it has a vascularized swim bladder allowing it to gulp air, an adaptation suited to warm, low-oxygen waters. Historic range declines have led to conservation attention in several US states.

Distinguishing an Alligator Gar from other gars and large predatory fish:

• Snout: broad and short compared to other gar species, resembling an alligator's jaw
• Teeth: a distinctive double row of large teeth in the upper jaw
• Scales: thick, diamond-shaped, interlocking ganoid scales forming natural armor
• Body coloration: olive-brown to greenish above, paler below, sometimes with dark blotches
• Fin placement: dorsal and anal fins set far back, close to the tail
• Size: among the largest freshwater fish in North America, often exceeding 1.5 meters

Its short, wide snout separates it from the Longnose Gar, which has a much narrower, elongated jaw.

Alligator Gar inhabit slow-moving rivers, oxbow lakes, bayous, and reservoirs throughout the lower Mississippi River basin and Gulf Coast drainages, ranging from Texas and Louisiana through Mexico. They favor warm, sluggish or still water with abundant cover such as submerged vegetation and woody debris, and tolerate brackish conditions in coastal estuaries. Their air-breathing swim bladder lets them survive in poorly oxygenated backwaters and floodplain habitats that many other large fish cannot use. Historically their range extended further north into the Mississippi and Ohio River systems, but habitat alteration has reduced their distribution in parts of the United States.

Alligator Gar are ambush predators that hover motionless near cover before striking quickly at passing prey with a sideways snap of the jaws. They periodically rise to the surface to gulp air, a behavior visible even from a distance and useful for identification. Generally solitary as adults, they can form loose aggregations in favorable habitat, particularly during the summer spawning season when adults move into flooded vegetation to release eggs, which adhere to plants until hatching. As a top predator in its ecosystem, the Alligator Gar helps regulate populations of smaller fish, and its long lifespan, sometimes exceeding 50 years, makes it one of the longest-lived freshwater fish in North America.