In other news, because I need to rant and no one reads this thread anyway....
I'm glad that Fish's tail is on the mend. I have a chronic tail biter, so I understand what you're going through!
If you don't mind taking care of the tank at work, then as VJM suggested, maybe offer to take care of it.
Who keeps buying the new fish? I'd think that would start to get rather expensive. Maybe talk to whoever keeps purchasing the new fish, and offer to work with him/her in order to keep the tank clean?