I used to see tons of these in a creek near my parent's house growing up. The creek was heavily polluted at times along with fish kills due to a photography company upstream dumping chemicals. These little buggers are tough, being about the only survivors from the chemicals.
Chara would be good cover for them, and other thick vegetation like FA and coon tail. I always found them tangled up in wads of vegetation. I may go get some from that now clean creek when I stop by my parents house this weekend. I hadn't thought of these, they are "free" and native!
