I would say that is somewhat true. It can be very relaxing, but also very stressful too. Another fish jumped out last night, and again, I was standing right there so he got back into the tank very quickly. I wouldn't say though that it was a calming experience.
It's interesting about the blood pressure. I am going to try and talk my mom into getting a tank for her house. If I do all the maintainance, maybe it will help my dad out a bit, heart wise.