As a high school teacher, I had a 10g tank, many potted plants, a worm farm, and even a hydroponic gardening setup. They all provided good lessons for the kids (even as a social studies teacher). Now I'm in college admin with a cubicle. I've thought about looking into the building rules to see if I can keep a 20 liter tank at my desk. Fairly small, but I imagine still a liability to have around. It never hurts to ask!