Hi Kiran,
Thank you for the kind words.
I think it might have been an O2 issue. I have four babies still swimming around this morning. If it was something toxic, wouldn't you think that they'd be all gone? Mysids are getting visibly larger and the tiny collonista snails I have in the tank as a clean-up crew are doing well, too.
I used a small round container for the larvae tank and had the air turned down to a slow gentle bubbles since some babies were getting blown around when it was turned up a little higher. If I save another batch in the near future, I am going to use a 5 gallon tank with two air bubblers on each end. I will probably modify my larvae collector to be gentler, too. I'm afraid that I am learning as I go. I hope the next time I can do better. It's so sad to see dead baby fish on the bottom of a tank.
Tomoko