Agkistrodon piscivorus is often a venomous snake, a types of pit viper, based in the southeastern USA. Adults are large and effective at delivering a painful and potentially terminal bite. When antagonized, they are going to stand their ground by coiling their and displaying their fangs. Although their aggression continues to be exaggerated, on rare occasions territorial males will approach intruders within an aggressive manner. This is the world's only semiaquatic viper, usually obtained in or near water, specifically in slow-moving and shallow lakes, streams, and marshes. The snake is really a strong swimmer and will even go into the sea, successfully colonizing islands off the two Atlantic and Gulf coasts.
Cottonmouth
The generic name comes from the Greek words ancistro (hooked) and odon (tooth), as well as the species name arises from the Latin piscis (fish) and voro (you can eat); thus, the scientific name translates into “hooked-tooth fish-eater”. Common names include variants on cottonmouth, swamp moccasin or black moccasin; also cottonmouth, gapper, or simply just viper. Most of the common names make reference to the threat display, where this species will frequently stand its ground and gape at an intruder, exposing the white lining of its mouth. Three subspecies are currently recognized, such as nominate subspecies described here. Its diet consists mainly of fish and frogs, but is otherwise highly varied and, uniquely, has been reported to incorporate carrion. source of wikipedia cottonmouth.