Pond Boss Forums INTRO Questions & Observations Trout Worms?

Here's the info (I found it again) from the NC State University site.
Ric
Fish Parasites
Wild fish normally carry a variety of parasites, and usually show no negative effects unless the infection is extremely heavy. Largemouth bass are commonly infected with the bass tapeworm, which lives in the intestine of bass; this species does not infect humans. Two other parasites frequently observed by anglers are the yellow grub, and the black grub or black spot parasite. The yellow grub is the larval stage of a trematode worm which forms small whitish or yellowish cysts in the flesh and near or just beneath the skin. Black grub parasites are also the encysted larvae of trematode worms, and appear as a small black spot about the size of a small pinhead, in or just beneath the skin.

Both of these parasites have a complex life cycle involving snails, fish, and fish-eating birds such as herons or kingfishers. The adult worms live in the mouth and throat of fish-eating birds, and shed their eggs into the water as the bird feeds. The eggs hatch and the free-swimming larvae infect snails. Later, advanced larvae emerge from the snail and penetrate the skin of a fish. When the fish is eaten by a bird, the cycle is completed.

While all these parasites are aesthetically unappealing, they will not infect humans and are killed by thorough cooking. There are no chemical treatments available to eliminate these parasites in pond situations. However, snails are a preferred food of redear sunfish, so establishing a good population of these fish in the pond may help disrupt the life cycle of parasitic trematodes.