Short answers, pulled from the story.
The English naturalist Philip Henry Gosse coined the word aquarium, combining a Latin root meaning water with a suffix meaning a place for. He used it as the title of his 1854 book, The Aquarium: An Unveiling of the Wonders of the Deep Water.
Philip Henry Gosse is known as the Father of the Aquarium. In 1853 he created and stocked the first public aquarium at the London Zoo in Regent's Park, a display first called the Fish House.
The aquarium principle holds that aquatic plants in a container of water give off enough oxygen to support animals, so long as the number of animals does not grow too large. The English chemist Robert Warington fully developed it and published his findings in 1850 in the Chemical Society's journal.
Fish and other inhabitants excrete ammonia, which is toxic at high concentrations. Nitrifying bacteria of the genus Nitrosomonas convert ammonia into nitrite, and bacteria of the genus Nitrospira convert that nitrite into less toxic nitrate.
A kreisel tank, named after the German word for spinning top or gyroscope, is shaped like a horizontal cylinder and is designed to hold delicate animals such as jellyfish and newborn seahorses. It provides a slow circular flow with minimal interior hardware so the inhabitants are not injured by pumps or the tank itself.
As of 1996, aquarium keeping was the second most popular hobby in the United States after stamp collecting. In 1999, an estimated 9.6 million American households owned an aquarium.