Buy American seafood, preferably from the West Coast; from Alaska is even better.
Extra points if it has the Marine Stewardship Council logo. Look for labels that overload you with good info, like where the fish was raised or caught.
Fish frozen at sea may be in better condition. Also, frozen fish transported by truck or ship have a lower carbon footprint than air-freighted fresh.
Overnight in refrigerator, to protect flavor and retain juices.
Immerse sealed package in a container of cool water. Change water often until fish is thawed.