The oft-overlooked National Aquarium in D.C. is fighting plans by the federal government to charge rent for its space in the basement of the Herbert C. Hoover Building, after putting in more than 70 years in the same location at no cost.

Not nearly as well-known as its affiliate in Baltimore, the nonprofit National Aquarium welcomes roughly 175,000 people a year to what Executive Director Robert Ramin called a “charming, intimate experience.” But it could face a financial crisis if it is forced to pay what the General Services Administration is seeking for the basement expanse.