Fish has a very delicate, light flavour. It is a healthy lunch or dinner option, not as rich as red meat or as filling as a pasta dish. The light taste is enhanced by sour citrus fruits or sweet exotic flavours like mango. Fish menus can be difficult if you are trying to find a complementary dessert. Chocolate dishes can be too rich or overpowering. You want to select a dessert that enhances and builds upon the flavours of the fish.
A key lime pie or lemon meringue pie would be a wonderful complement to any fish menu. It follows the sour citrus theme of the dinner dish. Neither of the two pies is a particularly heavy dessert. The cream or meringue on top adds a lightness and airiness to the dessert.
Fruit-flavoured sorbet would be a lovely complement to a fish dinner, especially if you complement the flavours. Mango is a common topping for fish like salmon or halibut. Serving a mango sorbet would be a nice touch to the palette, keeping the flavours similar.
You could serve a richer dessert if the fish dish was slightly heavier, such as fried cod fillets or butter-herb-encrusted salmon. If you want to treat yourself (you had a light dinner anyway, right?), you could opt for a rich creamy dessert like cheesecake. It isn't as overpowering as chocolate, but it is just as extravagant and decadent. Consider serving a plain cheesecake so as not to overwhelm the flavours of dinner, or opt for a fruit topping like strawberries or oranges.
Fish has a such a light flavour that it is often enhanced with exotic flavouring. Many Thai recipes enhance the fish with coconut, honey or curry. If the fish dish you served had Thai-inspired elements, consider making a traditional Thai dessert. You could make a Thai sticky rice dessert pudding that uses coconut milk and honey.
Fish is the ultimate diet food. It is low fat and delicious. But even when you're on a diet, you still need a little something sweet to finish off the meal. You can still have healthy dessert options that won't ruin your whole day, and which will complement the dinner you just had. One great choice is grilled fruit: pineapple, apples, pears, mangoes. You can serve them with a drizzle of honey or a glob of fresh cream.