The University of Otago's aquarium has been closed to the public after an engineering report showing the building is earthquake prone.
The two-storey building at Portobello was constructed in the 1960s and attracts 20,000 visitors a year.
University property services director Barry Mackay says the building, on the seaward side of the complex, has been assessed to be less than 15% of the new building standard for earthquake strength.
Mr Mackay says equipment and tanks in the affected aquarium building will remain, so that they can be attended to by research staff.
He says it is planned to immediately strengthen these areas with temporary propping and bracing to allow this.
Pro-Vice-Chancellor Division of Sciences Professor Keith Hunter says options for upgrading or replacing the aquarium facility "as soon as practicable" are being worked through.
The aquarium contains about 100 different types of fish.
The building that houses it is the smallest of the three main structures within the Marine Studies complex.
The larger 1980s-built marine laboratory immediately adjacent and the newer New Zealand Marine Studies Centre on the landward side of the complex remain unaffected by the temporary closure.
The outdoor fish-holding spaces underneath the 1980s-built structure next door, housing larger fish including sharks, is also unaffected.