If I have understood the experts here, FHM will reproduce very rapidly and give predators a good start if given time to build up before adding predators, but they are often wiped out. GSH will build fast and provide larger prey items, and will also persist if larger breeders are allowed to grow before being eaten. I have both in my YP/SMB pond. Not sure if GSH in a LMB pond may interfere with BG control.