You will probably not get predation from HSB like you would from LMB. They will certainly love eating pellets. But I would not stock HSB big enough to eat your BGxRES fingerlings.
The rule of thumb for LMB is that they will eat sunfish up to 1/3 their own length. HSB, having smaller mouths, might be able to eat sunfish 1/5 their own length (SWAG).