Thanks alan, I'll try out a wooden box and see how it goes, I've got a few lying around that should be suitable. I had wondered about them feeding on the mix instead of the food, but that's just something I'll have to wait through I guess because we don't have many pot plants around the house due to a member of the family with allergies. My fish should be fine in the meantime, I've got plenty of bloodworms, mosquito larvae and even daphnia coming from my ponds in spite of the lower temperatures, I feed them on yeast and they multiply crazily fast - I harvest almost every day to keep them overpopulating.