Can you eat raw tuna fish?

* Parasites: Tuna can harbor parasites like anisakis, which can cause severe gastrointestinal issues if ingested.

* Mercury: Tuna, especially larger varieties like bluefin, can accumulate high levels of mercury, a toxic heavy metal.

* Histamine: Improperly stored or handled tuna can develop high levels of histamine, which can cause scombroid poisoning, characterized by symptoms like nausea, vomiting, and diarrhea.

However, there are some exceptions:

* Sushi-grade tuna: This is specifically prepared tuna that has been frozen at very low temperatures for a certain period to kill parasites. It's important to ensure the tuna is labeled "sushi-grade" and comes from a reputable source.

* Ceviche: In some cultures, tuna is used in ceviche, where it's marinated in acidic citrus juice that breaks down the muscle fibers and kills some bacteria.

Important Considerations:

* Freezing: Even with sushi-grade tuna, freezing for a longer period of time (several days at least) is recommended to ensure parasite elimination.

* Freshness: Always prioritize fresh tuna and purchase from reputable sources.

If you're unsure about the safety of raw tuna, it's best to err on the side of caution and cook it thoroughly.