hi! I have a male koi betta fish named archie. ive had him for a year. about a month ago, he started acting weird, like laying at the bottom of the tank. I went to a fish forum where they kept telling me it was water quality so I flushed my tank, switched to tap, and more, but nothing is getting better and he is only growing worse. two things that are very notable is that his spine has curved DRAMATICALLY. and, when he swims, his bottom half sinks to the bottom as he tries to fight to swim up. i’m so worried and any help or tips will be a lifesaver! thank you!