The red-bellied black snake’s head is barely distinguishable from the body as there is no obvious constricted neck area. This snake is dangerously venomous but bites are rare because it is usually a placid and fairly docile snake, preferring to enact a lengthy bluff display with flattened neck and deep hisses rather than bite. It grows to a length of 2.5 metres, and is a very distinctive snake because of its simple and unvarying coloration. The upper surface of this snake is glossy black while the belly is light pink to brilliant red. The only other snake with a similar appearance is the small-eyed snake (Cryptophis nigrescens), but in this species the red belly colour is not visible unless the snake is turned over, where as the red of the red-bellied black snake extends up the lower flanks.
The red-bellied black snake is commonly associated with streams, rivers, creeks, swamps and other wetland areas. They may wander into well vegetated private gardens which are adjacent to water courses.
The red-bellied black snake specializes in eating frogs but they will also eat lizards, mammals, birds and occasionally fish.
Unlike other close relatives, red-bellies produce their young alive. At birth they are usually wrapped in a thin transparent membrane, which easily tears as the little snake wriggles to free itself. Up to 20 may be produced in one litter.