You can store cooked tuna in the fridge for up to 3-4 days or in the freezer for up to 2-3 months. To store your ahi tuna, allow it to cool to room temperature. Then, transfer the fish to an airtight container or wrap it tightly with a layer of plastic wrap followed by a layer of aluminum foil. To thaw, just place it in the fridge 24-48 hours before you plan on eating it.
Please note, that if the ahi tuna was previously frozen to start, it shouldn't be frozen again after cooking.