I recently stocked HSB and it took every bit of 4 weeks for them to start feeding. Like you I was beginning to wonder. My first clue that they were still in the pond came one evening when I noticed some fish feeding in a group, and in a manner I was not familiar with. They are very quick.... as in almost impossible to see, just flashes here and there. Mine feed in a loose school, and they're done in just a couple of minutes. But it's a frenzy while it lasts.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.