Hey Emeily i don't know why i am torturing myself and you. I just saw that you check out the forum yesterday ,and then decide to read all your posts over again trying to understand what went wrong. Still not sure why/what happened. He was fine all 39 days. I would think may be other betta that baby yellow one had something and you share anything between them. Or if you didn't rinse the IAL,or i don't know what else to think...
Also i spoke to someone who also has hard water and she had problem until she really acclimate betta for very long time.
I just really wish you can try one more time if you can. And like i wrote i will mail water conditioner, betta, if you want i can buy 2.5 gall tank. I will make sure betta is healthy. We can talk to the girl who has hard water so she can give you instructions on acclimation.
Anyways sorry to bother, i hope to hear from you. I guess you was too nice that is why i am writing to you again. I hope you have a good summer:)