Sorry Bill, I was referring to the ones that are 3 inches long and mostly black, I have no idea how to tell the species apart. My friends pond has some, probably 50 in a half acre pond. They are slowly increasing in number, but dont seem to be going crazy. His pond also has good visibility, much better than mine, but my pond is new and has not gone through a winter under the ice to settle thing, either.
I was just wondering how much of an effect some clams could really have
