In terms of the rent, he is only allowed to raise the rent a certain percentage every year if you are an existing tenant (at least in BC). My landlord does ~4% per year, but only does 2% for me because I take care of his house (ie. I do all the gardening, etc). Unless you live in a really pricey place (but I assume not because you're a student), $250 is rediculous.
Even if you convinced the landlord to not raise the rent and let you keep the tank, I'd still go. He'd never really feel happy with the situation and probably make the living arrangement uncomfortable. As it is he sounds like a bit of a dink
.
Time to go find a sweet new place!