How long can fresh ahi tuna be refrigerated?

Generally it is good until it smells bad or strongly "fishy". To eat the tuna raw or seared it should probably be eaten within 3 days of being caught. If you dont know when the fish was caught, rely on your nose. Beyond that, it is advisable to cook it all the way through. However, any fish that smells really strong should not be eaten, even if cooked.

One tip specific to tuna is that the fish will often lose moisture when sitting in the refrigerator. A smell may be associated with these juices. I use a paper towel to pat the fish dry and then smell it again. Some people even wash the fillets, but most purists advise against this as it can diminish the fish flavor that you paid big $ for.