Hastings Castle is being overrun with the augmented reality characters with no fewer than five spotted among the ruins including Zubat, Diglett, Drowzee and Pidgeotto.
They enlisted the expertise of a younger member of the team who confirmed the Castle was now home to a collection of Pokemon characters.
Blue Reef Aquarium’s Leanna Lawson said: “Some of our younger staff have been on a mission to track down as many of the different characters as possible in and around the Castle grounds.
Pokemon Go is an augmented reality game on smartphones. Players move around the real world in search of hundreds of virtual monster characters.
Pokemon first became popular in the 1990s when they appeared on the Nintendo Game Boy.
In the latest versions, which is already proving to be a global phenomenon, players can visit Pokestops – typically landmarks or buildings – and collect free items in the game.
The main aim is to catch Pokemon, which pop up along the way. The game provides an augmented reality experience, using the smartphone’s camera to provide a live view of the world, with Pokemon superimposed.
Any creatures caught can be used in battles against other players at Pokemon gyms.