An aquarium in Japan is shocking visitors with its Christmas display -- using an eco-friendly electric eel to illuminate the lights on its holiday tree.

Each time the eel moves, two aluminum panels gather enough electricity to light up the 2-meter (6 ft 6 in) tall tree, decked out in white, in glowing intermittent flashes.

The aquarium in Kamakura, just south of Tokyo, has featured the electric eel for five years to encourage ecological sensitivity.