Grilled fish is a great meal any time, but it takes some effort to keep it from overcooking or sticking. A coating of a little mayonnaise on the fish makes it easy to get it just right.
Photo by Didriks
If the fish sticks to your grill, it will fall apart and essentially be ruined. Kelli Dunn at The Kitchn recommends a simple way to avoid that:
An essential step to keep fish — both fillets and whole — from sticking to the grill is making sure it's coated with a layer of fat. While you can use cooking oil, like canola or olive oil, there's another kitchen staple I like to use: mayonnaise. Brush a coating over both sides, then season the fish before placing it on the grill.
There are a couple other ways to keep fish from sticking — using a wood plank or even a bed of sliced lemons — but the mayonnaise sticks to the fish better than other fats will and it also keeps the fish tender and juicy. If you don't like mayo, there's no need to worry. The mayonnaise flavour and texture isn't noticeable after you're done grilling. So if you like to grill fish, you might want to pick up some mayonnaise just for this.
A Little Tip for Successful Grilled Fish [The Kitchn]