Blackened in a black iron skillet in a gas grill. Did this last Friday and it was awesome. Tastes great even cold the next day on a salad or with dirty rice or on tacos.
Use margarine or real butter with Blackened redfish seasoning (I use a large bottle of Chef Paul's I have but not sure if it's sold where you are). Preheat the grill to about 400 deg with your skillet on the grill with no Pam or anything sprayed on it. Just the bare skillet. Melt butter and spread on fish, both sides. Liberally sprinkle and thoroughly coat fillet on top side with seasoning. Put fillet in skillet with blackened season side down. Let cook for about 5-10 minutes till almost dry burning the butter away. Enjoy the sizzle and take a swig from your adult beverage.
While it's in the pan, sprinkle and coat the bare buttered side of the fillet that's now up. When ready, take a fork or spatula and flip. The blackened season that was on the bottome side makes a kind of crust. Cook another 5-10 minutes or until butter sizzle is gone. Fish is flaky, moist and seasoned great. Works really well with thick redfish fillets, too. Enjoy.
Plan B is with a big trout fillet, cook on the half shell with skin side down on foil on the pit. Remove with spatula and skin stays attached to foil. I heard this on here already but hadn't tried it yet.