I have this girl betta that I was getting ready to put into a sorority, and I decided I didn't want the filter to have to adjust to the ammonia of 10 new girls all at once, so I put her and another girl into the divided breeder box (I only had 2 fish at the time) And this was around the 20th-23rd. One fish jumped INTO the breeder box and mauled her, like NO fins. The other fish was fine, though. The other girls have been there since the 16th and are all settled in, so I want to add one of my 2 girls (the other girls all knew each other already because they are sisters) Her tail is about halfway back. I think being out of the jar with ammonia will be good for helping her tail heal too, ut she will get some nips at first. She is about twice the other fish, so I'm not worried about her standing her ground.