Go find a seafood market and make your own frozen food 'flatpacks' ... ??
Grind up the scraps in a blender with a small amount of water.. put them in XL zip-lock bags and 'lay' them out in your freezer.. Vwa-lah, you have frozen foods!
They should hopefully key in on the 'smell' of the seafood, and gobble it down! A great inexpensive way to get those picky eaters some frozen food, especially if you can't find it in your country!