Put the noodles in a bowl of boiling hot water for 4 minutes, then drain.
Meanwhile, heat a medium saucepan to hot, add the laksa paste and cook for 1 minute.
Add the coconut milk, water and mushrooms then reduce the heat to medium to low and cook for 2 minutes.
Increase the heat to bring the liquid almost to the boil. Gently place the fish pieces into the liquid. Reduce heat back to medium to low and cook for 4 minutes