Well you, my friend, deserve a standing ovation for your efforts! That is a LOT of sick fish to care for and rehome. I must ask how you found homes for them all. Did you end up having to ship the fish? If you did, how did that go?
You are truly an amazing person and those fish sure were lucky to have you this year. As for next year, maybe call the board of education and make a petition of people who were also offended by this teacher's actions. Hey, if we can't have a Christmas party at school because people are offended (which I still don't get, why can't people just ignore it if they don't celebrate Christmas?) then why should animal cruelty be allowed if it offends some students.....it's all in the wording.
Did you take any pics of your room with all those fish in there?