These early exhibitions were successful enough that seven years later, the city of Philadelphia converted the traveling tanks into a stationary aquarium at Fairmount Park. One of the stars was a giant snapping turtle.

Philadelphia’s aquarium was part of a small but rapidly growing community of large public aquariums in the United States, including the Woods Hole Science Aquarium in Massachusetts (opened in 1885), the New York Aquarium (1896), and Detroit’s Belle Isle Aquarium (1904). Visitors were more concerned with wonder than education, and tanks usually contained local species, the occasional rescued family goldfish or donated lobster, and tropical fish. The aquarium keepers themselves had little interest in conservation. As aquarists developed the craft of holding aquatic organisms captive, many of the fish under their care died. In 1917, the Philadelphia aquarium received 663 fish for exhibition; by the end of the year, 454 had died.

Unlike zoos, which relied on specialty species such as tigers and elephants, early aquariums showed relatively common species—it was the very act of seeing underwater that drew visitors. By 1920, the earliest American aquariums had banded together to collect tropical fish for exhibition. Starting around 1915, a representative from the New York Aquarium traveled twice a year to Key West, Florida, where he collected a wide array of species. That same year, the assistant director and tropical-exhibits collector Louis Mowbray brought 148 animals from Key West to Detroit, including squirrelfish, spiny lobster, stone crab, a hawksbill turtle, two species of moray eel, and three of grouper.

The earliest aquariums had little concern for the impact their collecting might have on the health of a species or ecosystem. Charles Townsend, who became the second director of the New York Aquarium in 1902, knew firsthand through his work with the U.S. Fish Commission that the number of marine mammals was depleted in the wild. This did not stop him from seeking out porpoises, seals, and sea lions along the Atlantic Coast for exhibition. One of the last known Caribbean monk seals, declared extinct in 1952, spent the end of its life on display at the New York Aquarium.

Townsend never thought to use the aquarium as a space for mammal conservation, but he was not entirely inured to the decline in marine populations. In 1929, he imported some of the last Galápagos tortoises to aquariums and botanical parks around the United States and the Caribbean in an effort to save the lumbering giants from extinction. Until his death, Townsend kept close records of the tortoises, moving them to locations that he felt would have luck maintaining and growing captive populations. The year after he died, the first Galápagos tortoises bred in captivity hatched at the Bermuda Aquarium, and in the past decade, the surviving Townsend tortoises were returned to the Galápagos as part of the ongoing conservation initiative.