I appreciate the kind words everyone. Just an update...I slacked off with water changes in the endli tank for one day and lost a few as a result. Learn by my mistakes and be on your 'A' game with tiny fish!
I'm surprised about your endli though, honestly, they probably died because one of their siblings tried to eat them, but spit them out.
My endli grow-out tank got pretty dirty because I had a lot of snails in it (they were food for my puffers) but they grew fine and are in the bigger tank now.