Hydrolycus tatauaia is a species of dogtooth characin found in the Amazon, Orinoco and Essequibo basins in tropical South America.

[5] Like other Hydrolycus species, H. tatauaia has long pointed canine teeth that are used to spear their prey, generally smaller fish.

[5] The body and head are silvery, and there is a vertically elongated dark spot behind the opercle.

[3][7] It reaches up to 59 cm (1 ft 11 in) in total length and 2.7 kg (5 lb 15 oz) in weight.

[2] This predatory fish occasionally makes its way into the aquarium trade, but it requires a very large tank.