It would appear the name "fisher" has been taken by another player. If an account is not accessed for a long time, the original name becomes available for anyone to use, which sounds like what has happened in your case. More info about unavailable names can be found here
You didn't use the name for a sufficiently long enough period of time and so someone who actually wanted to play with it got it, names are occasionally recycled for people to use from accounts who are inactive.
Bossfishersaid: why though? this sucks, why do they get the name but i still have to log in as fisher?
Because you did not log into the account for a long time, so it was presumed inactive and the name was freed up for someone else to use. Unfortunately, if it's already been taken (as it has in this case), then there's nothing more that you can do other than adding to your desired name to your friends/ignore list and wait to see if they change it or it get force changed if they are inactive