A few fishy ideas

Pan frying fish with a simple sauce - ideal for most types of sweet, white fish, I like John Dory but use whatever is fresh.

Finely Chop some fresh parsley
Chop some capers
Cut a lemon in half

Put a frying pan on a medium-high heat with a little olive oil
Season the fish on both sides with a little sea salt and ground pepper - be a little heavier with the salt on the skin side as it will help it crisp up.
Once the oil is hot place the fish pieces skin side down into the pan
Don't move them around - if they start to curl then try to hold them flat using a fishslice
You should be able to see them cooking through from the side - once they are cooked just over 1/3 of the way through then add a good lump of butter to the pan and turn the fish over to cook the other side.
Whilst the other side is cooking use a spoon to keep marinading the skin side of the fish with the hot oil and butter - the butter will really improve the flavour, so you want to coat the fish as much as possible with it.
Once the fish is cooked through then place it on warmed serving plates and make a simple sauce....
Add another knob of butter to the pan, unless there is a reasonable amount already there - the butter should be foaming in the pan and starting to turn a golden-brown colour...squeeze half the lemon over the foaming butter, then add the parsley and capers - give a quick stir and then pour over the fish.

Simple Red Thai Curry
Make a simple red thai curry by frying some onions, finely chopped carrot in a pan - then add a glob of red curry paste and fry for a few minutes - add a can of coconut cream and simmer for 10 minutes or so to incorporate the flavours - adjust the seasoning to taste - add thai fish sauce to make it saltier, a little sugar to sweeten it and possibly some pepper. Add a few halved cherry tomatoes and a handful or two of fresh marinara mix and stir gently - turn the heat right down. Check every couple of minutes and once the fish looks like it is cooked, add some chopped thai basil and spoon into serving bowls with steamed rice.

A few other ideas - let me know if you want more detailed recipes

Fish Pies, or gratinated in a creamy sauce
Simply grilled - tuna steaks, swordfish steaks, etc...
Risotto - make risotto with white wine, fish stock, fennel then add frozen peas and chunks of fish when it is cooked.
Experiment with different sauces for the fish - lots of good simple combinations of wine, butter and lemon juice - use more robust sauces for the stronger fishes - parsley, capers, olives, anchovies, etc - can all be used as the bases for many sauces.
Look up a few poaching recipes - especially poaching in red wine, very spectacular as you cut into the red piece of fish to reveal the sparkling white interior.
Try a few less common varieties of fish - skate wings, arctic char are good at the moment.