Here are a few pictures of one of my crowntails. It looks like he is missing a lot of his fins, especially the tail. In fact, the fins are clear, so they are hard to photograph. I think you can see them in one of the pics.
Anyway, my wife said I should name him after I picked him up. At first I thought it ridiculous since they won't come if you call them, but she insisted. I thought for a minute and came up with a smart alec answer.
I told her that he looked Irish so I named him Gill-bert Fin-negan. The name stuck.
Just added some videos to YT: