If they're sort of large (by parasite standards) with a small disc at the base, they are anchor worms.
If they're very small but still visible at an angle (will look like fuzz or hair) they are a species of skin fluke that specifically preys on polypterids (their scientific name even includes polysterus or something, I can't remember off the top of my head).
Either way, anti parasitic meds such as jungle labs "Parasite Clear" have worked for me, so would coppersafe, but take caution you don't want to use copper safe if you're treating a community tank (especially if you have clowns with your polypterus).
I have some fuzzy shots of some wild caught polys that had this, I will look for the pics.
HTH