Scombroid poisoning is named after the mackerel family because those fish cause it most often, but the condition is really about one thing: how much free histidine the flesh contains. Mahi-mahi, bluefish and amberjack are all outside that family and all carry enough histidine to produce dangerous histamine levels when the fish warms up. Mahi-mahi and tuna are the two species named most often in outbreak reports.

Mahi-mahi grades high on histamine content, though it does not strongly liberate your own. The grade reflects the worst realistic case rather than a guarantee, because it is fragile. Histamine forms after the fish dies, not while it is swimming, so the same species can be perfectly low or genuinely dangerous depending on how long it sat above fridge temperature. Buy frozen at sea where you can, keep it cold on the way home, cook it the day you buy it, and do not save leftovers if you are histamine sensitive.

Yes, and that surprises people. Cooking kills the bacteria but not the histamine they produced, and histamine survives grilling, blackening, searing and freezing intact. This is why a fully cooked mahi-mahi steak can still cause flushing, a pounding headache and hives within an hour. It is a chemical dose rather than an infection, so it usually settles within a day, but severe cases need medical attention.

On paper yes, because it is graded compliant with paleo and AIP and clean on gluten, dairy protein, nightshades, every FODMAP column, salicylates, oxalates and nickel. In practice, a fish whose main trigger risk is entirely about storage is a hard thing to control during an elimination phase. A lean fish with a lower histidine load and a shorter supply chain gives you a cleaner test, and mahi-mahi is easy to reintroduce later once you know what your baseline is.