I don't see why not. Fish food is primarily fish meal anyway. I would boil them or in some way sterilize them to prevent any bacteria from getting in the tanks or other nasties but the fish may by more than happy to get a good taste of fresh food. After all they feed shrimp, beef heart, mealworms, nightcrawlers and other fresh food so why not!
That is a good idea BTW. Some of the trout I catch have eggs so I think I will try that this year. I will boil them first to sterilize them but I think it would be an awesome source of protein for any fish. Might even try it with the fish heart.
Is that much less that I have to throw away.