http://health.thewest.com.au/news/2166/its-true-fish-tanks-keep-you-calm-at-the-dentist
I can remember an incident at my Doctors clinic about 20 years ago, I had been sitting in his waiting room for about 15 minutes, and watching a large tank of fish, when he took my blood pressure, he got one hell of a surprise and asked me what I hade been doing, when I told him just watching his Gold fish, he said “that will do it every time.”