I cook a lot of my fish in the oven, with some kind of liquid to keep it moist (milk, sherry, white wine - depending on the recipe), and sometimes add a knob of butter too. Thinner pieces, such as plaice, filleted sea bass, skate, etc, don’t take long to cook at all in the oven, about 15 to 20 minutes. Keep an eye as they can quickly dry out. I set my temperature at 180 degrees C, slightly less if I use the fan oven feature.
I’m guessing your haddock is smoked haddock? I would cook that on the stove top in a little milk.
I very rarely fry fish.
I haven’t cooked thinner fillets of fish in the air fryer, but I have successfully cooked salmon steaks and cod steaks in mine - again adding a little liquid to keep them moist. They come out very tender and moist.
I realise I’m posting this a few days after you posted for advice Cillafan, so you will have cooked your fish by now. I hope you found the advice of other posters helpful, and enjoyed your fish 😁.