I had FW Mussels in a goldfish tank as a kid, When i moved out of home they got thrown into a tub at the back of the section with a few rocks, wood, no sand and some plants.
2 years later I was helping to clean up the olds backyard and come across the tub
The plants hadn't done so well but there were 3 mussels still alive. I was surprised that they had survived.
I put them in the goldfish pond where they could get around.