It sounds stupid but I lost the end result of a beta breeding project to his fins. His fins and tail were 150-200% of his body length. What this meant is when he tried to move all he could really do was send waves through his fins and tail. We though it was pretty hilarious when we thought it was harmless. Then he died.
When I mentioned this at the LFS I was told breeders back in Thailand trim the fins so as to keep top end breeder males from dying that way.
Well part of my butterfly koi's tail just fell off. I was not aware this was something that could happen. Parts of your fish are not supposed to just fall off.
The piece
The fish and a friend who tried its best to be between me and the one I was trying to get a picture of.
A close up
The fish seems to have not even noticed and they are both happy and healthy as far as I can tell.
Should I prune the fins and tail shorter?
Was this a weirdness never before seen, so I shouldn't worry about it?
Is there some defect in butterfly koi?
There isn't some sort of crazy cichlid like, Koi aggression, that I haven't heard about is there? Full moon? I'm sure I would have heard about that by now.