Do worms really live in the skin of fresh water fishes which do not have scales?

Answer 1

That is true! There are are certain kinds of parasitic worms such as blood flukes that attaches to a fish's skin and then forms a CYST in which it lives within the fish’s tissues.Those parasitic worms (mostly flatworms) mostly inhabit on the gills, fins,and skin of freshwater as well as the saltwater fish.

Answer 2

Yes this can and does occur even in aquariums. Scaled fish are more difficult to infect but they can also have external parasitic worms.