The Palau grenadier is a species of rattail

Rattail

Grenadiers or rattails are generally large, brown to black gadiform marine fish of the family Macrouridae...

. This is a deep-water fish found at depths of up to 710 m. It has been recorded from many parts of the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 including Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, southern Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, Palau

Palau

Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...

 and northern Taiwan

Taiwan

Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

.

This species is rather similar to many of its congeners and is best distinguished by a combination of morphometric characters. It has a fairly distinctive black pattern on its head and a uniformly dark first dorsal fin

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

(although this latter is not a unique trait).