kiddie pool still stumps me

I'm still trying to get my still water kiddie pool going, but I cant keep
the fish alive. I have been using small rosey reds or feeder comets 2 or 3
of each. The comets frequently die over the first night. One of the roseys
made it a week. Lethargy and hiding is the only symptom I have seen. The
water parameters are perfect but the fish sure arent. I have a couple of
baby lilies, a handful of submerged plants, some floaters and a small taro.
The only thing different than my thriving pond is no filter or pump, its
shaded and water temp is 12 degrees lower (76), it is not sunk yet, and
unknown plastic content. I have been floating the new fish bags for about
30 minutes. I used it in the spring to hold plants while doing a PP
treatment (also treated it) and numerous tadpoles and several 'can barely
see them they're so small' fry were fine. It was in the sun then but water
temps were probably similar because of the season. My two best guesses at
the problem are 1)toxic plastic, although it is the same blue plastic
variety you see all over and many report using successfully and 2) no
algae=starving the fish. I have tried giving them a little flake food but
never seen them eating it. This was going to be my ultra low cost temporary
fix for wanting more plants and no mosquitos. Any ideas?

Bill Brister