Baked Mackeral with Rice

1-1/2 to 2 Lbs. Skinned Mackerel Filets
2 Med. Onions, Cut into rings
2 Cups Cooked Rice
Seasoned Salt (to taste)
Fresh Black Pepper (to taste)
Sprinkle Filets w/ spices and set a side
Put rice in bottom of foiled baking dish
Place 1/2 Onion Rings on top of rice
Place fish on to of Onion Rings
Place rest of Onion Rings on top of fish
Put a few pads of butter on top of fish (optional)
Green Peppers or Cajun Seafood Seasoning can be added.