Heat the olive oil in a skillet. Add onion and garlic and begin to saute. Cover and cook until softened, about 5 minutes (if onions begin to stick add a spoonful of water to the skillet and continue to cook).
Add the red wine, clam juice, capers, and thyme and bring liquid to a boil. Simmer over low heat until reduced to 1/2 cup.
Right before serving bring the sauce back to a simmer and add the fish. Cover and cook over very low heat until the fish is just cooked through, about 5 minutes. Remove from heat and swirl in butter and parsley (don't worry if fish falls apart).
Adjust seasoning and spoon into deep plates over rice, potatoes or garlic croutons.