In recent years public aquariums have grown in number and their popularity has increased. In today's increasingly competitive economic times, aquariums are using their popularity to earn revenues to support their capital and operational costs. Although philanthrophy still exists, most institutions must earn their own support. Such economic reliance presents the risk of losing the critical primary focus on the ethics and practice of maintaining and displaying living organisms. Living collections are the secret of the success of aquariums but they place serious responsibilities upon aquarium professionals. Allegiance to ethical practices, which should include conservation and education, will help to assure the continued success of aquariums. In addition to the living organisms that are the heart of an aquarium, new trends (but with historic origins) in exhibition techniques promise to make aquariums more exciting and popular. From habitat replication to integrated film programmes, these methods and materials will enhance the popularity of aquariums and make them even more successful in building appreciation and sensitivity for the natural world. Examples are given mainly from North America but also from around the world.