Do fish know it's Christmas?

The fishy charges of the Madrid Zoo's aquarium exhibit have been treated to a special Christmas tank makeover, and their keepers say they like the improvement.

Divers have installed a giant nativity scene inside a 10,000 litre fish tank, home to Toro the bull shark, as well as other species. 

The underwater nativity has become an annual tradition at the zoo.

Marine specialist Javier Garcia says it helps break up the monotony of the fishes’ everyday life.

“They know it is Christmas because something different is happening,” he says. 

"The nativity scene doesn't particularly bother them, in fact it takes them out of their routine," he says.