In 1974 opens "aquarium hall" in the basement of the museum, which has become a favorite place for hobbyists and visitors. Situated on 100 square meters is the largest freshwater aquarium in the country.

In conditions close to natural shows 37 species of rare tropical fish from different countries of Asia, Africa, Australia and America.

During the last 2012 was made partial repair of the Aquarium. Today the hall has 26 freshwater aquariums, home to about 150 species of tropical fish, 21 species of native fish (mostly from the Maritsa River). This year renovation was done by placing the 3,000 liter saltwater aquarium.