I can cut the oil down a bit by rinsing in cold fresh water just before freeding and by not adding to much. you get oils from alot for the frozen foods and home made foods. so I would say not much different than that It will only be the fish eggs as the rest of the gut can contain parisites and other pathagins. don't want that when frozen all bugs should be killed off but may not be. Eggs sacs are independent from the gut sac it would be hard for a pathagin or anything else to cross over. I use to feed salmon eggs my fish when I lived in Kamloops 20+ years ago and it was ok just not to many at a time and only once a week as Christy said watch how much I feed. My tanks have tons of surface movment so not top worried about a little oil.

Bill