I have a black halfmoon betta I got in February. He was quarentined for 3 weeks then placed in a 10 gallon tank I had split for him and another male betta. He was fine until mid-March when two tiny sections of fin were gone after the other betta got through the divider. I seperated them again then the black halfmoon began to lose more fin. So I put him in a 3 gallon with aquarium salt critter keeper, cleaned weekly, and he just lost all of his fins, literally. I know it can't be water quality because all levels were normal when tested and the other male was and is still completely healthy. Also there were no signs of fungus. This betta while in the 3 gallon would bounce around like a ping pong ball hitting the sides of the tank (woke me up at night several times). Now he is in a very small container floating in my 29 gallon since it has a higher temp I was hoping it would help. He has gained some color and hasn't freaked out since he was moved. Any explanations? Could he just hate "large" spaces and he chewed all his fins off? I've had probably 14 bettas throughout the years and have never had a problem like this. Thanks!