You sure can! My partner, Ross, eats a banana every single morning, and guess where he puts his banana peel? He tosses it in the rose garden. They dry right up and you don't even notice them in a day, and the roses love them. Make sure when you bury the fish remains, that you remember where you buries them, wouldn't want to dig them up again too soon! Phew!
Actually, my grandfather used to bury fish under his roses and peonies all the time - many years ago of course, but the reason still holds true!
Feed them well and they will grow to love you, and you will grow to love them!