White-blotched River Stingray

The whiteblotched river stingray is a very dark freshwater ray, deep black above and scattered with large yellowish-white spots, that lives only in the Xingu River basin of Brazil.

It is found singly in clear water over rocky bottoms, spending the day buried in sand and coming out to forage at night. The underside is mostly brownish-dusky. Females grow larger than males, and can weigh up to 20kg. Two close relatives look much the same, so where a fish was seen is a useful clue.

It feeds on invertebrates living on the bottom. Like other rays, it settles over its prey, pins it against the riverbed with its disc, then flexes the edges of the disc to steer the food into its mouth.

Its defence is a venomous spine in the tail, and although rays usually move out of harm's way when approached, a sting can be very serious. Never swim over the top of a large ray, since it may take you for a predator and whip its tail in defence.