It's important to get your dad on-side, as he's the one paying the water bills (which will most definitely increase), and the electricity bills (running those lights isn't cheap!). With this in mind, here are three good University-related reasons to get your own fish tank;
As someone who has just successfully finished a three-year course at Uni, I can tell you that three of the most important character traits you'll need to develop to survive your new-found independant University life are
personal accounting (budgeting),
time management, and a sense of
personal responsibility.
You'll need to be able to budget in order to survive. Food and rent aren't cheap (neither is beer

), plus most beginner students aren't used to budgeting
in advance(I.E. your student loan will come at a set time every term, and you have to stretch it as far as possible using paychecks from perhaps a part-time job to buoy the coffers).
I can tell you right now from first-hand experience that a fish tank is a major money sink, and someone without a stable income has to budget very carefully to be able to afford all the equipment, plants, and stock required.
Time management is a skill that again, most beginner students have no idea about. At secondary school and 6th Form, your lessons are pre-timetabled for you in set blocks each day, and you do your homework as you get assigned it. Brilliant. University is different. You'll have to quickly learn how to plan your battle strategy in order to get to all your lectures, conduct your research, write your essays, and not to mention carry out a copious social life. Hours are different too - not to mention your lectures will most likely be spread over different venues.
Having your own fish tank will teach you the benefit of regular scheduled maintenance, water changes, etc., and also help you to learn to adapt your routine at the last minute ("Argh! Is that fin-rot?!") - both of which are very useful when dealing with the challenges student life often presents.
Personal responsibility is very obvious. You don't go to lectures or do the coursework, you don't pass the exams and get your degree. Simple as. Mummy and Daddy aren't there to drag you out of bed in the morning, make your breakfast and help you with your homework, and the university aren't bothered - they've got your cash already. The onus is on you to step up and prove you're worth the financial outlay going to University costs these days.
With a fish tank, it's up to you to ensure the tank is clean and properly maintained, and that the fish are well-fed and healthy. They rely on you to live, and you're 100% responsible for them. This extends to ensuring you have the financial means to care for them as well.
Ben.