Just had another thought.

If your forage fish are strictly for consumption by predators (rather than for establishing a population in the big pond), you could use the lack of skills at avoiding predation to your advantage.

For example, instead of transferring all of your forage BG at once, you could transfer 10% every 2-3 weeks. The predators could gorge themselves on stupid/clueless forage. The remaining BG would continue to get larger in the forage pond. Rinse and repeat.

By the end of the season you would then be feeding larger BG to your larger predators. Win-win if you have a relatively easy way to transfer your forage fish.