I culled another 10 white cloud fry this morning. Scooped out the smallest ones- There's still about twenty left- so must have originally been eighty hatched! I think I will quit culling now and grow these out another few weeks, then give half to a fishkeeping friend who's asked for some, and grow the remaining ten to adult size before introducing to my window tank.
I've found it's easiest to remove fry from the tank with just a plain plastic soup ladle. I scooped them all into a small container and then added one more guppy fry that just showed up in the 33L. The guppy must have been only a day or two old- and it's twice the size of the three-week-old minnow fry. That's how small the white cloud fry are.