For the sauce, mix the grated rind of lemon and the yogurt in a bowl. Add the lemon juice, salt and pepper. Leave it aside.
Mix the grouper fillet, the egg white, salt and pepper in a bowl. Add the fresh cream, and place the bowl in a bigger container full of ice-cubes to keep cool. Incorporate the crab and the chives. Form 3 cm (just over 1") round balls and coat them in bread crumbs. Press down a bit if you want.
Fry the fritter 4 to 6 minutes in very hot oil. Add salt and pepper to your taste.