Well, failure struck overnight! There were quite a few dead ones floating, and quite a few that were on their floating on their sides swimming in fast circles when I went to clean the aquarium this morning. I took most of them out -- dead, alive, or swimming in circles, and dumped them into an empty growout pond. Surprisingly, a lot of the ones that appeared dead, came to life, and a lot of the ones swimming in circles took off too. I'm going to keep feeding them ground fish feed. I've already taken a bunch of chopped up worms to them, but I couldn't tell what happened. Tomorrow I plan to get some dried krill to grind up and feed to them in the growout pond.
