Cook the potatoes in boiling water for about 8 minutes until tender.
Heat the milk with the bayleaf in a large shallow pan with the salmon and white fish and simmer for about 3 minutes and then add the scallops. Turn off the heat.
In a separate pan heat the butter and gently soften the shallots, carrots and mushrooms.
Add the fish and cooking liquid, drained potatoes and cooked prawns.
Stir in the creme fraiche, dill and season to taste.