Place haddock fillets at bottom of crock-pot in a single layer if possible.
Mix tomatoes, oregano, pepper, garlic powder and wine in a small bowl.
Pour over fish.
Cut lemon in half and remove seeds from one half. Reserve other half.
Squeeze juice over the fish mixture.
Cook on high for about 2 hours.
Remove with a flat spatula or spoon, carefully.
Fish is ready when it flakes easily.
Slice lemon and serve on top of fish if desired.
You do not want to layer too much fish but if you need to cook a larger amount you may. Cooking times may need to be adjusted. I made this in a 6.5 quart crock-pot and the 4 fillets covered the bottom overlapping slightly. We had this over rice with the sauce spooned over it.