Krøyer's deep sea angler fish

Krøyer's deep sea angler fish ("Ceratias holboelli") is a species of fish in the family Ceratiidae, the sea devils. This deep-sea anglerfish is found in all oceans, at depths of 0 to 4,400 m (0 to 14,436 ft), but mainly between 400 and 2,000 m (1,300 and 6,600 ft). 
Females typically are 77 cm (2.53 ft) long, but can reach 120 cm (3.9 ft). The much smaller males only reach 16 cm (6.3 in) and they are symbiotic, as they attach themselves to a female.