Ted Pietsch, University of Washington professor of fisheries and aquatic sciences and curator of the UW fish collection, said this is the only completely albino ratfish fish ever seen till date.

According to Prof. Pietsch and doctoral student Jon Reum, the foot-long female may have been two or three years old, a probable teenager in the ratfish world.

Prof. Pietsch described the fish as almost pure white with a crystalline layer near the surface of its skin that gave it a silvery sheen.

Reum said he caught the fish in about 200 feet of water during a UW research project examining the food web in Hood Canal and Puget Sound.

Puget Sound is the US’s second-largest estuary in the Lower 48 after Chesapeake Bay. The city of Seattle, home to about 4 million people, is built on its shores. Puget Sound connects to the Pacific Ocean via the Strait of Juan de Fuca to the north.

"Ratfish usually hang out in places with soft, muddy bottoms. The typical ratfish in Puget Sound is brown or black with a smattering of white spots so it blends in with the sediments," said Reum.

Prof. Pietsch said it was also surprising to find the specimen alive, as spiny dogfish are known to have a liking for ratfish.

"Why didn’t it get eaten, long before this, by some predator, for example, by a spiny dogfish so common in Puget Sound and that love to devour ratfish," said Prof. Pietsch.

Albinism, found among mammals, fishes, birds, reptiles and amphibians, is a form of hypopigmentary congenital disorder, characterized by a lack of melanin pigment in the eyes, skin and hair.

The condition is rare in sea life and only a handful of albino sharks have been sighted. But albino ratfish have not been seen before, though they are common and abundant in many places around the world.