[jinx]

"White tuna" is one of my favorite sushi orders. For years I had no idea what it really is.

wiki
Like its relative the oilfish, Ruvettus pretiosus, the escolar is consumed in several European and Asian countries, as well as in the USA. Neither fish metabolises the wax esters (Gempylotoxin) naturally found in their diet, which causes an oil content in the muscle meat of the fish amounting to 18–21%. These wax esters may rapidly cause gastrointestinal symptoms following consumption; however, these effects are usually short lived.
The gastrointestinal symptoms, called "keriorrhoea", caused by these wax esters may include oily orange diarrhea, discharge, or leakage from the rectum that may smell of mineral oil. The discharge can stain clothing and occur without warning 30 minutes to 36 hours after consuming the fish. The oil may pool in the rectum and cause frequent urges for bowel movements due to its lubricant qualities and may be accidentally discharged by the passing of gas. Symptoms may occur over a period of one or more days. Other symptoms may include stomach cramps, loose bowel movements, diarrhea, headaches, nausea, and vomiting.

Escolar is sometimes consumed raw as sushi or sashimi. It is also sold misleadingly as "white tuna", "butterfish", "oilfish" and "Hawaiian butter fish"; in Hawaii and Fiji, it is known as walu.