The fish in the North Sea Museum Aquarium, which sprung a leak after a fire earlier this week, have started to die.
The 8m/26' deep tank, which is the largest in Europe, split and started leaking millions of litres of water into the cellars below. The life support system was also put partially out of action.
The Museum's Chief Biologist, Henrik Flintegaard told The Guardian: "We know that some of the fish are still alive but some are dead because we can only see a few swimming about".
Divers are currently attempting to rescue the remaining fish and are pumping oxygen into the water to boost the dissolved oxygen content.