New to this group so please bear with me. In July, 2012, my husband and I were using a small net in our shallow creek (Town Fork Creek, southern Stokes County NC) to collect interesting critters for a small aquarium. I had previously kept SA tropicals. We caught some minnows, a couple of crayfish and a 2" odd hatchling who turned out to be a Marginated Madtom. Fast forward to present day. The madtom is a robust 8" fish who shares a 30 gallon tank with a mature Festivum (8") and a gold gourami (4"). Unlikely tankmates, I know, but the madtom is just so cool. I'll admit he's snacked on a few smaller fish through the years.
About six weeks ago the Festivum (a SA cichlid) developed a couple of small (2 mm) round cyst-like nodules between the rays of his tail fin. I kept an eye on him, but didn't observe any changes - until yesterday morning when I noticed half a dozen white, pimple or worm-like protrusions on his head. I first checked my resourced for tropical fish diseases and parasites and nothing quite fit. Then, doing an image search, I found pics of 'yellow grubs' in FW native fish that really looked like what we have. My research indicates that the parasite is transmitted via fish-eating birds (we have herons).
My question: could this parasite have remained dormant in the madtom all this time and jumped species only to emerge under stress? (I was hospitalized and couldn't do my regular water change for a couple weeks) Is it treatable and if so, how? The first photo is of the Festivum's head, the second of "Tom".