You get your “goat cuisine” merit badge for choking down that metal can. The Canadian Food Inspection Agency does not require Best Before Dates on any food with a shelf life … If you refer to the contents; may I just say that there is not an “expiration” of canned food but a “sell by” date. Use canned tuna by the expiration date on the can. As a general rule of thumb, most canned foods (for example, canned tuna, soups, and vegetables) can be stored for two to five years, and high-acid foods (canned juices, tomatoes, pickles) can … Do not use leaky or rusted cans, toss them immediately. If the can doesn't have a "best by" date, mark it with the date of purchase and use the tuna within 12 to 24 months of purchase. Therefore, you should rotate your cans and follow the first in, first out rule to ensure you don’t end up in this predicament of having to determine if canned goods are too old to eat. If you open the can and anything is brown or black, then do not eat the spam, tuna, canned chicken, or corned beef. Eat canned tuna as soon as possible after purchase to ensure that it is the best quality, texture and flavor. There are, of course, certain health risks associated with spoiled foods so always remember to practice food safety and enjoy your foods before their shelf life has expired!