My oldest Betta whom I have had for about a year was exhibiting strange behavior just a few minutes ago. He was 'twitchy'. I really don't know how else to explain it. He also seems like he was having troubles keeping his back side from floating upwards and he was bending in half. He doesn't look like he has any specks on him or 'dust' but he does have a lighter colored belly and his head down to half of his body is a brownish color.
He was recently moved to a 5 gallon tank about three weeks ago and since has been much more active and swimming rapidly back and fourth across his tank, but since it has been going on so long I figured it was because he has so much more room since I moved him from a one gallon tank. The tank is filtered and I did a 50% change just yesterday, using prime. There is a bit of ammonia in my tap water but his tank is starting to cycle out the ammonia. It was at 0 when I did the water change yesterday.
He does dig in the substrate sometimes but I haven't seen him flash against any tank decorations. I also have some white cottony like stuff (algae or slime mold?) on his new decorations that I have been cleaning off when it appears. His poo is long and brown.
I've been having issues getting any good pictures of him since he doesn't sit still! Here is the most recent one I have, though.