Final answer:
The necessary documentation for sushi-grade fish delivery should confirm that it was frozen to safeguard against parasitic infections such as fish tapeworms.
Step-by-step explanation:
When receiving a delivery of sushi-grade fish, the correct documentation that should be included from the supplier is that the fish was frozen. This is essential because freezing fish at the correct temperatures is one of the accepted methods to kill worms and larvae, such as fish tapeworms, potentially present in raw or undercooked fish. Ingesting fresh raw fish can increase the risk of parasitic infections, making it crucial for sushi-grade fish to be handled correctly to ensure safety while maintaining its quality for consumption.