Erythrocles schlegelii, commonly known as the rubyfish or Schlegel's red seabream, is a medium-to-large deep-sea fish belonging to the family Emmelichthyidae under the order Perciformes. It is widely distributed in the northwestern Pacific Ocean, including waters off Japan, Taiwan, and China’s East and South Seas.

The fish has an elongated oval, laterally compressed body with a vibrant red or pink coloration and fine, shiny scales with a metallic sheen. Adults typically range from 30 to 50 cm in length, with some individuals exceeding 60 cm. It inhabits continental shelf and slope waters at depths of 100 to 300 meters, dwelling in mid- to lower-level zones, and feeds on small fish, crustaceans, and cephalopods.

Renowned for its delicate texture, low fat, and high protein content, Erythrocles schlegelii is rich in nutrients and has a sweet, clean flavor. It is suited to various cooking methods and is especially valued in Japanese cuisine for dishes such as sashimi, salt-grilled, or simmered preparations. Its striking color and excellent taste make it a prized ingredient in festive or formal meals, contributing to its high culinary and commercial value.