Wanted to give a big thank you for all advice given in my recent horror experience with harlequins. I lost every one of them, I had put two swordtail fry in towards the end to see if they were affected by water conditions, but they were fine. But I took all advice given, larger qt, nothing fancy but that will stop me, hopefully, wanting to graduate it from a qt. And I, very nervously, tried another eight harlequins (from a different lfs). Which are all surviving after six days and even starting to colour up....so relieved. It was very hard not to keep checking on them every ten minutes. So thanks!!