The Tlilcoatl (“black snake”) or Acoatl (“water snake”) is a long, powerful snake found in the swamps and waterlogged caves of Mexico. This glossy black snake is thick enough that a man’s arms can just barely wrap around it. The scales are a glossy black in color. The head is large, with blazing eyes and beardlike appendages at the back similar to those of the barbel. The tail is bifurcated.
The powerful mouth of a tlilcoatl can generate a suction strong enough to draw in prey from a distance. Tlilcoatls feed mostly on fish, but they are not above drowning and eating people. They can spit venom as passers-by, incapacitating them enough to suck them in, pull them underwater, and devour them.
Sometimes a more elaborate stratagem is required. A tlilcoatl will dig out a small pool and stock it with fish to serve as bait. It pauses after depositing a new catch of fish, looking around, then going back to get more. It is tempting to profit from the snake’s absence to steal fish. But the tlilcoatl, standing erect, easily detects thieves, and chases them so fast that it seems to fly over the grass. Once in the snake’s coils there is no escape; the tlilcoatl pushes both ends of its tail into the unfortunate victim’s nostrils (or any other opening) before squeezing the life out of them.
There is, however, a means of stealing a tlilcoatl’s fish cache and escaping alive. All that is required is a hollow tree. When chased by the serpent, would-be fish thieves should hide within the tree. The tlilcoatl will coil around the unyielding trunk and squeeze so hard that it dies.
Nuttall, Z. (1895) A Note on Ancient Mexican Folk-lore. The Journal of American Folklore, v. 8, no. 29, pp. 117-129.
Sahagun, B. (1830) Historia General de las Cosas de Nueva España, v. III. Alejandro Valdés, Calle de Santo Domingo, Esquina de Tacuba, Mexico.