So the fourth one (out of the picture above) wasn't as bold as the others, found him this morning bobbing at the surface.
So the final tally is three out of six made it. Damsels should have a better survival rate than this, but small sample size doesn't prove anything.
Other three should make it - they are almost eating out of my fingers at this point.
Sending another email to BlueZoo to see if credit has been applied to my account yet, as I'm tempted to get a few more before seeing if it was a fluke or not. In my favor is the seven day guarantee ends today, so I should be getting credit for them all.