Fillet the fish and set aside the fillets to cook later, de shell the prawns and clean all the seafood.
In a large pot on medium heat, add the butter, then the prawn shells and saute them until bright orange. Add the onions, celery and carrot and continue to saute until nicely brown.
Add 2.5 litres of water, and the fish bones and bring to a simmer. Let it simmer for about 20 minutes. Skim the surface of fat and debris intermittently.
Set aside and let it cool down; then strain out all the ingredients; leaving you with only fish stock.
Cooking the dish
Bring a large pot on medium and saute the onions, garlic, celery, potatoes, mushroom with olive oil until fragrant.
Deglaze your pot with white wine, ensuring that you reduce the wine by half - then add your herbs in w/ your canned tomatoes.
Add your prepared stock in. And let the base simmer over and reduce for about 20 - 30 minutes. You want the consistency to be between a soup and a thick sauce.
Finally add all your seafood in (portioned fish fillets, clams, mussels and prawns) and let it stew for approx 15 minutes with a lid on to steam.
Serve it hot!
Seafood Variety - Nothing here stopping you to add on crabs, scallops, cockles, oysters or what every seafood you found at the market.
Fish Picking - Really any types will do; however, this dish was intended for cheaper fish varieties that you could easily: descale, gut and fillet. Expensive fishes with subtle flavour will be lost in this dish.
Seafood Cheat - Buy frozen and prepared; but it doesn't taste as good.
Fish Cheat - Buy frozen and pre-filleted; but it doesn't taste as good.
Stock Cheat - Stock Cubes, Stock Pots, Pre-prepared stock can be replaced instead of making your own.
Herb Cheat - You could replace with dried herbs instead of fresh. If you do, just make sure you put them in early to rehydrate (cook off).
Adding More Flavours - Some capers, fresh chillies, smoked anchovies, lemon zest would give it some extra zing.
Canned Tomatoes - This is kinda a requirement; since there is a distinct lack of fresh pomodoro tomatoes in Singapore, we'll have to use the canned variety.
Condiments - I've seen people like this dish with some mustard, aioli or some chilli.
Sides - Serve with some toasted herbed (or garlic bread) or cous cous or a nice rice pilaf. Anything that could really soak up the stew.