My kids each got a betta fish several weeks ago and we got nice tanks with lights, low flow filter, and habitat enhancers. I have not done a 100% water change until last night. I rinsed everything out with plain water, refilled the tanks, put each fish back and we woke to find both of them dead.
I feel horrible and am definitely in the doghouse with my kids. They were doing a good job feeding them and taking care of them and we would like to get more bettas but I need to understand what happened before I harm any other fish. Any input would be greatly appreciated. This looks like a good site for general betta care info so I'll keep reading the general stuff.