It is native to southeastern Asia but has spread to other parts of the world, including Australia, South America, southern Europe and the United States.

The body surface is covered with tiny papillae and is a uniform red to dark reddish-brown colour, sometimes almost black.

On the ventral surface, there is a central accessory copulation pore next to the gonopores, but this is absent in young animals.

[3] As is the case with all leeches, B. weberi is a hermaphrodite; sperm is passed from one individual to another by traumatic insemination.

[5] Adults are often found attached to water plants, and the cocoons containing eggs are attached to rocks, submerged objects or aquatic vegetation at the base of leaf whorls; it seems likely that the transport of aquatic plants by the aquarium trade is the means by which the leech has dispersed to new locations.