We have a 1/2 ac pond that currently has no structure and limited vegetation. I'd estimate between 500-700k gallons. We have planted cat tails, water lilly, hyacinth and there is some plant growth, perhaps coontail. There is a large population of golden shiner, although at this point I'm not certain because of their dark green backs and silvery bodies, sunfish of all sizes, BNM and other bait species I have not identified in small numbers. We will be getting 30 SMB in a couple weeks given to us which I think would do well with no other predators. They are supposed to be in the 3-8" range.

At what point would structure be required to keep the shiners from being decimated? The bigger ones must be around 5-6" and pretty thick. The sunfish are from fry up to maybe 9" but I rarely see the bigger ones feeding on pellets. I have lots of 4" corrugated pipe, 6" hard pipe and other pieces I planned to make artificial habitat using stainless screws and cement block.

Would the SMB be pellet trained if they are hatchery fish?

As far as I know the pond has never been managed.