The plans include a new tank and viewing tunnel as well as two external panoramic lifts which will take visitors up to the roof of the concrete tower.
The panoramic view from the rooftop over Vienna is stunning, but can currently only be seen by people who have paid to enter the aquarium - or choose to climb the 192 steps on the outside of the tower.
"Currently we are doing preparatory work for a new aquarium on the ground floor. It will hold more than half a million litres of seawater. A tunnel will be built through the tank, which will offer new perspectives of the sea life,” aquarium director Hans Koppen said.
Construction is scheduled to start in the autumn and should be finished in time for summer 2016.
The new panoramic lifts will ease pressure on the single internal lift and take visitors directly to the roof cafe, without them having to buy a ticket for the aquarium.
Koppen said there are also plans for a new balcony on the 10th floor, which will be covered and offer fantastic views of the city, whatever the weather.
The revamp will cost around €6 million.