There's a guy who posts on the possibility of nematodes in wild worms.
LOL... almost sorry I saw this thread.
In any case, that would be me, although some people seem to misinterpret what I've posted as 'don't feed red wigglers' or as a simplistic 'there are nematodes in worms', neither of which is a fair representation of the information I've posted. That earthworms can harbor a variety of parasites (not just nematodes) is a fact that is well known to those who do research on them and is a consideration in some of the research into their potential for various animal feed, including fish-- example
here, where in the introduction it clearly says:
their ability to harbour parasites and pathogens may constitute a problem to their use as inclusion in animal feeds
...and when the subject comes up, yes, I sometimes point this out regarding live wild earthworms. Exactly which pathogens they harbor can vary with species of worm and the habitat in which they're found.
To what extent this poses a risk to your fish, or whether or not to feed them is something you'll have to figure out for yourself, as that's a debate I'd prefer to stay out of here.