In my world there are merfolk who live in their own underwater civilization. They are sapient with unique and complex social customs, and one of them involves food.
Just like on land, merfolk royalty hold banquets/dinner parties. Cooking for merfolk is basically sushi, fish and crustaceans are sliced into pieces and arranged to look aesthetically pleasing.
One potential problem is that due to being underwater, the food might float away, and so merfolk might need to come up with a way to force the meat pieces to stay in place.
How would merfolk accomplish that?