Do you know whether or not you have leaky gut syndrome? If you do, this could be a newly acquired allergy to tuna fish.
An allergic reaction to tuna can cause red, itchy skin like hives. The itchiness can occur within minutes of eating or handling tuna and can last as long as four hours, sometime longer. Swelling around the eyes and lips is not that uncommon, but then again, may not occur at all.
Another cause could be something called sulfites. This is a preservative that lots of different foods contain. They can be listed as sulfite, sulfur dioxide, metabisulfite, or bisulfate. But the listing isn’t required if it’s a small amount. Sometimes tuna will contain one of these. Interestingly, foods that naturally contain high amounts of this are onions, garlic, and cabbage, but my thought is that the naturally occurring amounts wouldn’t be as likely to cause reactions as when it’s used as a commercially manufactured additive.