I have also ordered 500,000 ,,,,s and want to grow them a bit before releasing them. I don't havemuch experienece so i wnate to vet my ideas here before putting it together this weekend.
300 Gallon Rubermaid Tank placed in my pond with waterline 6' to a foot below top. Subemersible pump would pump fresh pondwater w/ nutrient/foodstuff into tank continuously. Bottom feeding overflow drian buried in large gravel, so fry are not sucked out of tank.

screen over top to prevent jumpers and interlopers. Hopefully the pond water would keep fresh food coming in but I would supplement with some sort of pellet. Release after 4-6 weeks

What do you think?