As a part of my culling phase I've been cleaning quite a few BG and came across this one. Fortunately I've seen this in only a few but this one was pretty bad. Some were on the outside, some were imbedded in the flesh.
But I've also seen it in the gills of a few LMB, like this one:
I saw no indication on the outside of the BG such as spots, sores, etc.
I'm assuming this is some type of parasite or worm?