bichir tail

I have a new bichir fish and it eat sometime but it floats on the top of the circuits all day long and I think it broke can somebody help me

When I first got them, they already had their tails bitten off pretty close to the flesh. The tails grew back slowly but seems to have stopped growing halfway at a completely different shape. Instead of pointed, they are completely flat ended. Like instead of > it is ]. It doesn't seem to be...