Hi - I've had my yoyo loach for about six months now, and within the past few weeks he has developed a strange behavior where he flips on his side and does a weird violent twitching motion. He did this once when he had ich, but now he is doing it while seemingly healthy. I have been adding Melafix just in case, but he continues this behavior every once in a while. Again, though, he seems to be in perfect health except for this sporadic behavior. What could this mean?