Grill most fish over medium high heat, except tuna which should be seared over high heat and left with a cool center.
Fish is done cooking when it begins to flake easily.
Don’t turn fillets. You can turn steaks such as Tuna, Mahi, Halibut, Salmon etc. But the fillets will fall apart.
I always cook my salmon at 400 degrees.
How long depends on the thickness.....be careful not to overcook it.There are many Oven Baked Salmon Recipes that I also tried instantly.
If the fish has skin on one side, grill it skin side down then when the fish is done separate the fish from the skin with a spatula. Dispose of the skin.
Also consider cooking delicate fish wrapped in foil with citrus or on a cedar plank for even cooking.