My fish definitely relieve my stress. And since I have tanks in every room of the apartment (except the bathroom ), it's easy to just turn and watch the little guys. They always make me smile.
I don't have stress yet They can get boring, because all mine do is sit still, and stare at me, or they get sick with some kind of incurable parasite *cough* bolivian rams got nematodes *cough* and get me frustrated. Fish that ignore me are cool, or fish that do things to get attention