I’m sure you will get a nice dish without using them, but Maldive Fish Chips are probably the most unique and essential ingredient in Sri Lankan cooking and as far as I’m concerned can’t be omitted.
I’ve heard that bonito flakes could be used as a substitute however I can’t attest to this. They are funny like things, like bits of wood chips, they impart a peculiar salty, fishy flavour in a similar way for example that fish sauce does to Vietnamese or shrimp paste does to Malaysian .
To buy them, you’ll need to locate a Sri Lankan grocery store. If you are in Sydney, I buy mine from Spiceland at Flemington, which is also the place I buy my all my spices from.
Sometimes you might find the fish chips are quite big (as you can see from this photo), therefore give them a quick whizz in your spice grinder or mini food processor to make them a bit smaller.