Heat the olive oil in a large saucepan over a medium heat. Add the garlic then stir in the turmeric, salt and pepper and cook for 3 minutes, stirring from time to time. Throw in the fish pieces and cook for 5 minutes, turning occasionally.
Pour in the stock and water and bring to the boil over a high heat. Cover the pan, reduce heat to low and leave to simmer gently for 10 minutes until the fish is just cooked through.
Meanwhile prepare clams. Discard any with damaged shells or ones that dont shut when lightly tapped. Scrub the shells clean and rinse thoroughly under cold running water. Drain.
Add the clams and squid rings to the pan then cover and leave to cook for about 5 minutes until the clams have opened and the squid is tender. Discard any clams that fail to open. Check seasoning.