as much as I hate sayign this.. go to your local petco/petsmart.. get a care sheet on jack dempsy's.. or online print one off. and "magically make it appear" on said teachers desk.. if that hint doesn't work.. a more direct approach is desirable.. makeing it Anon in this case may be the best approach. direct confrontation of student/teacher may work, or may end up w/ a teacher who's disgruntled. If the teacher doesn't change things, head to the principle.
What she's doing is animal abuse, and it's teaching kids animal abuse. It's not acceptable. she needs to change her husbandry, or get rid of the tank.