Well everything that relaxes out brain is good is beneficial to us. I find fish very relaxing and a perfect pet for a person with mental diseases. Their grace calms down your mind in every situation. On the other hand, they don’t need your attention or your time which is again a plus. And the aquariums are not only about fish, you can put other underwater animals in there, like startfish. worm (some beautiful ones I saw on https://arcreef.com/bristle-worms/bristle-worms-fireworms/). Plus, the aquarium is highly customizable, which can keep your attention away from problems.