Preheat a grill to medium-high heat (375 to 450 degrees Fahrenheit).
Bring the fish to room temperature for about 15 minutes. (For salmon, in a shallow dish mix together 4 cups room temperature water and 3 tablespoons kosher salt. Place the salmon in the water for the 15 minutes.)
Grill the fish over indirect heat for 4 to 5 minutes (skin side down if there is skin), until it releases from the grates. Flip and cook another 2 to 4 minutes, until the internal temperature is 130 degrees (right when it starts to flake when pulled with a fork). Allow to rest for a few minutes, then serve.