I've had this crowntail for about a month. I've never seen him eat a pellet, only freeze dried bloodworms. (I've posted about this before) I don't think this is the cause, but a symptom. But anyways, the past few weeks he has kept his fins clamped and is swimming in odd jerks. He usually just sits on the top or in his cave. I had him in a heated divided tank, but he got worse and I've moved him to a 1/2 gallon ISO so I can observe him better and do daily water changes... but I don't have it heated. It's around 76 degrees and his tank before was 80. Would one of those mini heaters work in a 1/2 gallon? Should I use aquarium salt? I've had fish long enough to tell when something's wrong, and this is defiantly on of those times.
I think it's also worth nothing that his color is still wonderful. I'll try to get a pic up, but they don't do much. Just show a clamped up fish.