I hope the SMB guys jump in here, and some construction experts.
I am thinking my SMB will get to 3-4 pounds. I hope so. I also hope they reproduce. I dumped a lot of 8" rock in, and built gravel beds on top of that.

9 yr old pond, 1 ac, 15' deep.
RES, YP, GS, FHM (no longer), HBG (going away), SMB, and HSB (only one seen in 5 yrs) Restocked HSB (2020) Have seen one of these.
I think that's about all I should put in my little pond.
Otter attack in 2023