It seems to fit quite well with the metacercaria which I describe as Clinostomum complanatum in terms of host, site and appearance. This has previously been recorded, as C. complanatum or C. marginatum, from Phoxinus eos in Ontario on more than one occasion. Big worm for a small fish!
Gibson, D.I. (1996) Trematoda. In: Margolis, L. & Kabata, Z. [Editors] Guide to the parasites of fishes of Canada. Part IV. Canadian Special Publication of Fisheries and Aquatic Sciences No. 124. Ottawa: NRC Press, 373 pp. doi: 10.1139/9780660164038
I would like to if you could send me his contact information or get in contact with him. I would like to see if he got the package and if he identified the organism.