Eating these fish can cause keriorrhoea (a kind of diarrhoea) in some people. This is because these fish contain an indigestible wax which is a natural laxative.
Susceptible people will usually develop symptoms within 30 minutes to 36 hours. The condition is not ongoing or life threatening.
No cooking or handling practices of these fish can prevent keriorrhoea.
It will benefit your business to warn customers buying these fish of the potential side effect.
These fish have been sometimes mistakenly mislabelled and sold as rudderfish. It is important, and also a legal requirement, to correctly label these fish.
Escolar Lepidocybium flavobrunneum
Oilfish Ruvettus pretiosus
Rudderfish Centolophus niger
All images: CSIRO