the tank was put there by the owners to create a bit of ambience in the restaurant
and quite possibly a tropical marine was selected to create the "wow factor"
obviously the original posters dining experience was less than expected owing to his understanding of what a marine tank should be
sad to see a restaurant and a very public owner that prides himself on the finer details of dining out let this slip
maybe he is too busy with other commitments or just doesn't know how a marine tank should be run