If you want to get your family to like fish, you need to start slowly, especially if they aren't used to it. Frozen fish is generally terrible, in my opinion. Freezing breaks down the cellular structure of the fish and leaves it mushy and often strongly flavored and rather odorous (i.e., it stinks, and it tastes like a fish cannery smells). I'd either dump the unidentified frozen fish or make a fish soup or stew with it, which hides the problems.
The biggest reason people don't like fish is that they've never had good, fresh fish properly prepared. Too often it's overcooked, which makes it taste and smell awful, and ruins the texture. Bleh!
Get some good fresh fish, and cook it using the Canadian Fisheries method -- 10 minutes total for each inch of thickness. Doesn't matter if you fry, broil, or grill, that generally works. BTW, I hate (most) baked fish.
I'd suggest fresh salmon, which is moist and flavorful. Halibut can be good, but it's often a bit dry and bland, especially if cooked a bit too long. Chilean sea bass is a universal favorite, as is tuna (ahi) but they're expensive. Mahi Mahi is a good choice, too, as is most cod -- mild flavor, sort of meaty texture, moist. Shark is somewhat like steak, as is swordfish -- mild, too.
Most people like fish grilled on the BBQ -- easy, eliminates the smell, and it tastes great just plain. Oil the grill and the fish well, and season it with salt and pepper. Cook it like a steak until it's still a little opaque or raw looking in the middle -- it will be fine by the time it's on the table. Again, overcooking ruins fish -- you want it moist. Serve it with lemon.
Frying may turn off your family due to the smell, which can be quite strong indoors unless you have a very good range hood.
I've attached (I hope) a few favorite recipes that even fish haters have found appealing.