With all the loaches you have, you should be able to leave the mussel in until it is an empty shell. They can't eat the most sinuous tissue that holds the mussel to the shell, you have to net that out.
I was hesitant at first to do multiple species, but they get along so well. I have one Burmese Spotted and one YoYo, and I believe that they think they are the same species, they shoal together.