It is extremely important that you know what the tuna that you bring home from the grocery store is supposed to look like, just so you will be able to avoid getting food poisoning from potentially dangerous bacteria that can grow on this type of fish if it is not properly stored or kept around for too long a time.

Pure red tuna meat tends to have the same texture and taste as filet mignon, so you will at least have something to compare it to when trying to figure out if it is still good. If your tuna has a sort of greenish color and a very pungent fishy smell, it will be important to throw it out immediately because chances are it has bacteria on it that you will not want to ingest.