Fish is debated on a low histamine diet. The SIGHI list scores frozen fish as 0, so low histamine on their scale but does note the presence of other amines. In their advice on cooking fish, the Swiss Interest Group Histamine Intolerance state that 'fish should never defrost slowly in the fridge or at room temperature. Do not refreeze food that has defrosted'. Take the fish straight from the freezer to the air fryer to cook, serve immediately and do not store. It should be noted that consuming fish on a low histamine diet is debated, so it is best to consult with a dietician to determine whether it is suitable for you. Have a read of my low histamine meal prep post for more on using the freezer to plan ahead!