Using a zester or vegetable peeler, remove the zest from the lemons, limes and oranges. Be careful not to zest too deeply into the white, pithy part of the fruits, just the colored parts. Reserve the zest ans set aside.
Cut the fruit in half and squeeze 2 halves of each fruit over the fish. Rub 2 tablespoons of the olive oil over the fish and season liberally with salt and pepper or Hi Mountain Gourmet Fish Seasoning
Heat 1 tablespoon oil in a medium-hot skillet, add fish and lightly brown on one side.
Scatter sliced onion over shark
Add garlic over onion and flip onion, garlic and fish over. Reduce heat to medium to prevent garlic from burning.
Add the juice from remaining lemons, limes and oranges. Squeeze directly over fish. Add remaining tablespoon of oil to pan, distributing evenly.
Fish should be done in just a few minutes. Make sure that there is always a little liquid in the pan to keep the garlic from burning.
Remove fish from pan and whisk butter and reserved zest into pan until butter is just melted. Spoon over fish immediately or butter will separate and make the sauce greasy!