QA gifted me with 97 Virile crays two summers ago. I stocked them in my main pond.
Now there are thousands of them. I trapped a couple hundred of them last summer
and moved those to my bait pond.

Haven't noticed them tunneling in the banks at either pond.

I toss the carcasses of fish that I butcher into the bait pond for the crays to clean up.
They also get any varmints that happen to meet their doom while raiding Mrs. Augie's
flower gardens and bird feeders.