I read that you should occasionally change all the water in the fish bowl...I treated water with calcium and nutrafin and left it for about 24 hours for it to match room temperature. I put my fish in a baggie with his old water, filled his bowl with the new water, and floated him in the baggie in the water for 20 mins before releasing him into the bowl. He was spazzing out a bit in the bag and when I released him, he went to the bottom on his side gasping. He's still doing so after 20 minutes. He looks like he can't swim properly when he tries but I don't see any fin damage. I've changed the water before but never had this problem. What might be going on and what can I do to fix it?