Yup, once they start biting it usually becomes a habit. Even if something was causing them to bite and you eliminate that cause. I can't wait to see pics of your little one.
Mercury is still fighting, he has been fighting for about 5 days now. It was so sudden. On the day I first noticed him like it, he was acting totally normal then suddenly I found him on the bottom of the tank with laboured breathing. His condition did not change or worsen until today. He has gotten worse today. :( I am doing everything I can as well as give him space to recover on his own. I will keep you updated. :)
Haha I have a few tail biters amongst my boys. I believe its to do with the extra space meaning they have to swim further to get somewhere and therefore they reduce the drag of their beautiful fins by destroying them. :/ The boys in the spots with the most filter current bite theirs too. Don't listen to those who say it's boredom! It's not true, why don't they do it in tiny cups/barracks?
I am glad your boys are good. :) And thats cute! I want to see some pictures of Perseus. Don't worry too much about Lucifer. He probably won't stop. Just love him to bits. :P My 16 boys are great except for Mercury. He is acting very weird and I have consulted experts and no one knows what it could be. He has very laboured breathing and gulping for air and 5 of my other bettas in the same water are perfectly fine. One minute he acts normal and tries to get attention or food and the next he is laying on the bottom breathing like that again. I don't think he will survive the night. :(