This complex was designed to make visitors feel as if they were moving below the surface of rivers. The open-topped aquariums, enjoying natural lighting and opening onto large windows, contain over 6 000 species of freshwater fish from various European regions; they can be seen in five separate areas focusing on different themes: migratory fish, discovery (observation laboratory), predators (the finest specimens of gleaning catfish are over 1.5m/5ft long), diving and tropical fish. Visitors, accompanied by a biologist, may feed the fish.