What common first-aid measure is recommended immediately following a scorpion fish sting?

Soaking the affected area in very hot water as hot as can be tolerated without causing burns.

When an accidental sting occurs from contact with the venomous spines of a scorpion fish, the immediate response should focus on minimizing the effect of the venom proteins. The generally accepted first-aid protocol involves submerging the stung part into water that is as hot as the individual can bear without sustaining a thermal burn. This high temperature is critical because it aids in the denaturation process of the venom proteins, effectively breaking down their structure and reducing their harmful effects on the tissue before systemic symptoms can fully develop. This measure is preventative against severe localized reactions.