In Daniel Knop's book "Giant Clams" he talks about this on page 110.
"Oysters and mussel are parasitized by several species of Planaria (Littlewood and Marsbe 1990), but in the <i>Tridacnidae</i> only one species of the family <i>Stylochidae</i> has been <b>described</b> and only in <i>T. Gigas</i>."
It goes on to describe the flatworms as being "very small and of brownish coloration". They enter the clam through the byssus orifice and can kill the clam.
Now, what to make of all this. Well, if Flame indicates that Dr. Ron says it will be ok...then why not. I respect his opinion on most everything. Besides Knop only indicates this happening with one species of the family. Although, from his description it sounds earily familiar to the reddish brown planaria widespread through the hobby today.
I guess it will be up to the rest of us to monitor and report and negative effects on our Clams with planaria present.
Anyone else keeping clams in a system with lots of planaria??
FWIW