Used to love Nutramar Ova, but that is nearly impossible to find. Not sure if it's been discontinued, or just seems to be out of stock everywhere.
Still have a small flat pack in my freezer, I save it for finicky eaters, but seeing as the tamarin is eating pellets, I'm not worried about it quite yet. Certainly has not lost any weight, and actually seems to be getting "thicker".
While I do not go to petco too often(I do buy my PE calanus there as they always have it in stock), I don't think I have ever seen frozen fish eggs in mine.
Do you happen to have a brand name? I'm all for trying new foods, and if it's as good as Nutramar Ova, I'm all in.