- Keeled scales, usually in rows of 21 to 27 near midbody.
- Divided anal scales.
- Dark crossbands on dorsal surface and dark ocular stripe.
Two subspecies of Nerodia fasciata are distinguished by dorsal background color.
Yellow or cream colored ventral surface.
Adult Nerodia fasciata commonly average between 56-106.5 cm (22-42 in) in length.
The three subspecies of Nerodia fasciata cover many of the southern U.S. states. Found in the western half of the lower Mississippi River valley, N. fasciata is also found along the coast of the Gulf of Mexico, from Texas to Florida, and along the Atlantic Coast, from Florida to North Carolina.
Non-venomous, Nerodia fasciata hunts fish and a wide variety of amphibians, particularly frogs. A nocturnal hunter, N. fasciata spends the day resting in the vegetation along the water's edge or hides deep in rodent burrows along the bank. Many species of Nerodia are suspected of being venomous cottonmouths (Agisktrodon piscivorus) but the behavior of the two snakes is tremendously different. Cottonmouths move much more slowly in the water, often keeping their entire body afloat. When threatened, cottonmouths show off their namesake white lined mouth in a defensive posture. All species of Nerodia are quick, agile swimmers which move rapidly through the water and water snakes never gape open their mouths if threatened. They may instead flatten their bodies in an attempt to look larger.
Like all Nerodia, N. fasciata is viviparous and may have give birth to as many as 50 live offspring per litter. These neonates measure 19-26.5 cm (7.5-10.5 in) when born during the early summer months and are more brightly colored than their parents.
Both subspecies of Nerodia fasciata prefer heavily vegetated lakes and ponds, though both are occassionally seen along canals and streams.
The southern watersnake is not a protected species in Texas and can be legally collected with a hunting license.
In Texas, Nerodia fasciata confluens is found in the eastern third of the state. Nerodia f. pictiventris is restricted, at present, to Cameron County, having been introduced there in the first half of the century from Florida.