Our salt water aquarium is somewhere you can go on underwater safari to discover the creatures that are hiding beneath the surface of the sea in Danish (coastal) waters. Many begin their life as fry in the Wadden Sea, then migrate into deeper water. Most of the creatures that inhabit Danish waters are here in our salt water aquariums.

In the aquarium hall you can look at, touch and get a feeling for life under the surface.
You can experience the large shoal of herring in our cylindrical shoal aquarium, and in front of our giant aquarium containing 100,000 litres of water you can stand on the sea bed and watch cod, sharks and rays swim about together with other deep-sea fish.

In the smaller aquaria and our touching pool, you can get close to the creatures and feel, for example, the shin of a small-spotted cat shark, a turbot or starfish.

The salt water aquarium in the Fisheries and Maritime Museum is made up of two independent systems – a quarantine tank and an exhibition tank. Each one’s water supply is independently treated. Both tanks are supplied with sea water pumped in beneath the museum from the Wadden Sea.

First, a drum filter removes all impurities larger than 60 microns from the incoming seawater. Then the water is put through a protein skimmer to remove any protein, and dyestuffs are burnt off with ozone. Any remaining impurities are caught with sand filters. Now only dissolved substances such as nitrites are left. These are converted to nitrate in our elevated tank which works as a bio-filter. The water is then irradiated with ultra-violet light to kill viruses, bacteria and algae.

The aquarium’s salt water is cooled to 14°C and is continually oxygenated, and the salt content is adjusted to roughly 30 parts per thousand. Its pH value is about 8, and lime and various trace elements are added as required. The temperature of 14°C is a compromise – some of the aquarium creatures prefer it warmer, others from deeper waters in the North Sea would like it colder.

The exhibition tank holds approximately 300,000 litres of water. The water is circulated around the plant 24 hours a day at approximately 130,000 litres per hour. Our objective is to change all the aquariums’ water once every hour. About 10 per cent of the water is replaced every week.