It was actually the guy at the petstore where I go every week, I stay awhile and shoot the breeze sometimes. When I first found one, I went right over there and asked what the heck that thing was? I really wasn't sure it was a leech. He stuck his finger right in, it latched on, I squealed "eeek!", he swung it around, it held on, and finally fell on the floor. Then he picked it up and threw it in a tank with a big fish that promptly ate it. I think he likes doing things like that to impress the ladies.
I've found a total of four in each tank. I found one soon after the one above that I posted, which made me decide OK, I'm changing the tanks out.