Cerviche.
Skinned and cubed with the red flesh removed.
In enough Lemon juice to cover the cubes for 30 to 120 minutes.
Stir this every 20 minutes or so.
When the flesh is white - ish drain the Lemon juice well.
Add enough coconut creme to cover the fish.

Add finely sliced Spring Onion, Capsicum and tomato. Some salt and pepper.

Buy the lemon juice in the yellow bottles from the supermarket if you don't have a source for lots of lemons.
Don't let the lemon juice overcook the flesh.

The tomato and capsicum is optional but the onion is mandatory IMO.