I went back to that PetCo today, the one where I repeatedly asked the manager and the fish specialist to change the water.
And they told me that almost all of the bettas had made it, and that "it was because of you, really."
I pointed out that the fish specialist had done all the work, and they said that the red barrel had been contaminated and offered me a discount on any betta in the store.
I thanked them, looked for a couple of hours and talked myself out of several gorgeous fish!
I bought a heater on sale and feel useful.
There were two amazing halfmoon plakats (one a doubletail) there, and some pretty half moons.
One of the baby bettas is a blue double tail.
Sooooo much temptation!
Prana (deep blue/purple CT female) Fluval Spec 2
Qi (turquoise CT female) 5 g riparium
Vanilla Beast (Ivory apple snail diffusa), Watson and Crick (Amano shrimp), Tributary (Moss Ball aka AquaTribble) Fluval Spec V
Pond and ramshorn snails (so many!) 2.5 g
Mr. And Mrs. Smith (assassin snails) 0.5 QT tank
Leopard ramshorns 16oz NPT Mason Jar