Purchased 20 freshwater clams and dispersed them between 3 tanks (3 in a 10 gal, 7 in a 29 gal and 10 in a 65 gal). 10 are still alive and (judging by weight) they are doing well. They definitely help keep the tanks healthier and cleaner. Unfortunately lost the 10 in the 65 gal. when I treated with maracide
Could see a difference in the detritus collection at the next water change.
When they died the shells opened and what looked like white mucus clumps were left - a pain only when I found them AFTER the tank cleaning. I did see a blip on my water parameters but since I was doing twice weekly water changes it didn't affect anything.