Tuna should not be thawed on the counter at room temperature. Tuna can be thawed in the refrigerator (8-12 hours) or using a cold water bath (~30 minutes). Frozen tuna steaks that are vacuum-sealed should be removed from the packaging prior to either thaw method. Thawing tuna in its vacuum seal can promote the growth of harmful bacteria. Tuna can be stored for up to 48 hours in the refrigerator after it has been thawed.