Coffee is one specific species of a bean, roasted, and brewed with varying amounts of hot water, milk, chocolate, and maybe a few other ingredients.
There are endless species of fish, with wildly different tastes (salmon, vs tuna, vs tuna belly, vs monkfish liver, vs catfish, don't tell me you can't taste a difference). In addition to fish, there are crustaceans (crab, shrimp, lobster, etc), mollusks (oyster, clam, squid, octopus, cuttlefish), and probably other major animal types I'm omitting.
The comparison is not adequate, sushi is inherently more diverse than coffee.