This might sound stoopid, but--what kind of protective hood is on the aquarium, and what kind of access do libraray members have to it? Being a teacher of many destructive young people, my first thought was kids messing around with it if they can get to it at all, OR well-meaning folk who end up developing a relationship with a fish or all and "feeding" them in that old well-meaning but destructive mode. Just a thot. . . r