I'll offer my 2 cent opinion, from observations in my trout pond which has heavy GSH population and not very heavy PKS pop. is that GSH help control the PKS's from over populating by being an aggressive consumer of fry.
This works well in my pond as the trout have plenty of forage, both PS & GSH while consuming very little trout pellets.
Of course with variables in water PH, temps. and long frigid winters make it hard to say this will work in other ponds.
The best scientific answer is "it all depends".
