[header] How to blacken fish [title] Heat a dry cast iron pan over medium-high heat. [step] A cast iron pan is a required tool for blackening fish, as other pans aren't capable of delivering the intense heat needed for this preparation. Set the pan onto a charcoal grill or a propane burner set to medium-high heat. 
Allow the pan to heat for about 10 or 15 minutes, and do not add any oil to the pan. [title] Melt some butter in a shallow pan.