The marbled whipray (Fluvitrygon oxyrhynchus) is a little-known species of stingray in the family Dasyatidae, native to several freshwater rivers in Southeast Asia.

It is characterized by numerous heart-shaped dermal denticles and tubercles on its upper surface, as well as a reticulated pattern of brown blotches on a light background.

The marbled whipray has been assessed as Endangered by the International Union for Conservation of Nature (IUCN); it is heavily threatened by fishing and habitat loss, degradation, and fragmentation.

In 1913, Samuel Garman synonymized this species with Himantura uarnak, a judgment that remained unquestioned in subsequent literature until Maurice Kottelat referenced the name in his 1984 review of Indochinese fishes.

[3][6] There are numerous flattened, heart-shaped dermal denticles on the back, arranged in a dense central band reaching the base of the tail, and becoming smaller and sparser on the outer portions of the disc.

The dorsal coloration is white to light gray, with brownish hexagonal blotches forming a reticulated pattern that fades towards the disc margin.

It is an infrequent incidental catch of intense fishery activities taking place across much of its range, using demersal tangle nets, fish traps, and hook-and-line.