I've read through every thread on this topic at this point and I haven't found an answer. I have a betta in a filtered, cycled, heated 2.5 gal tank with silk plants and a cave. He was full of personality and doing great for about two weeks since I got him. I have been doing small (up to 25%) water changes every 4 or 5 days with no issue. Ever since I did a water change this morning he's been sitting on te gravel, hiding, and not responding to anything (ahich he usually does). When he swims, it's erratic and panicked. I happened to check the water before I changed it and I checked recently again. There are no changes. Ph around 7 (a bit below). No nitrites or ammonia. Tiny bit of nitrates. I did an emergency water change from a different water source. Still acting weird. He's wedged himself between some plants and sits there unmoving. No visible signs of illness. Was gasping before but now he's just sitting and not being his usual chipper self. With all that out of the way: What can I do now? What might be the problem? (It's not tank size, which seems tk be the go-to answer around the internet - he was happy and active before this water change). I have a 29 gal established tank. Can I use water from there (as long as the parameters are the same)? Will that help? I really don't want this guy to die as I've grown attached in just these two weeks. Please point me in the right direction. Water temp is at 80 degrees. I used water conditioner and tresszyme before adding new water. Only other weird thing I've noticed is slight foam at the top of the water when I changed it. But none when I changed it again. Please help!