With a mouth full of teeth and the ability to grow up to six feet long, the alligator gar is a fearsome fish. It is also making a comeback in area rivers.

CHICAGO (AP) — A giant fish that once swam from the Gulf of Mexico to Illinois is making a comeback.

Biologists are restocking alligator gar in several states where it disappeared about a half-century ago, partly in the hope that it will be a powerful weapon against Asian carp. That invasive species has been swimming almost unchecked toward the Great Lakes for decades.

The alligator gar is the largest fish native to Illinois. It is a prehistoric species that has not been seen in the state since the last documented alligator gar catch occurred in the Cache River cutoff channel in southern Illinois in 1966. It was officially declared extinct in Illinois in the 1990s.

The IDNR began an alligator gar reintroduction program in 2010, but it has been on hold for the past two years. However, state lawmakers are working on a bill to re-introduce the fearsome fish, with the goal of enlisting it as an ally in the battle against the invasive Asian carp.

It turns out that alligator gar have a taste for carp — and also dwarf the invaders. Asian carp can grow to 4 feet and 100 pounds; alligator gar can grow more than 9 feet and 300 pounds.

The larger fish was exterminated from all but the southern part of its range by anglers who mistakenly believed it threatened sportfish.