I am an undergraduate biology student.
Recently I was advancing an academic project, on the presence of protists in the gastrointestinal microbiota of freshwater fishes. I found in the intestine of Prochilodilus magdalenae something that seems to be a parasite but I have had difficulties with its identification.
I attached a picture of a fish stomach content sample stained with lugol. I think it is a type of flatworm egg but I'm not sure and I don't want to rule out the possibility that this is a Protist.
Does some has some idea of what is that?