oilfish

The oilfish, scientifically known as Ruvettus pretiosus, is a species of snake mackerel found in temperate and tropical oceans worldwide. It belongs to the family Gempylidae and is characterized by its elongated body, large eyes, and a distinctive row of sharp spines in front of its dorsal fin. Its coloration typically ranges from dark brown to purplish-black.

Oilfish are deep-sea dwellers, inhabiting depths of several hundred meters. They are solitary hunters, preying on smaller fish, crustaceans, and squid. A notable characteristic of the oilfish is the high oil content in its flesh, primarily composed of a waxy ester called gempylotoxin. This high oil content can cause gastrointestinal distress, such as oily diarrhea or anal leakage, in humans who consume it. This phenomenon is known as keriorrhea. Due to this, consumption of oilfish is discouraged or regulated in some regions.

Despite its unpalatable reputation for some, oilfish is consumed in various cuisines, particularly in Japan where it is often mistaken for or marketed as "black cod" or "butterfish." Preparation methods often aim to reduce its oil content, such as draining or searing. Its commercial availability is generally limited due to the potential health concerns associated with its consumption.