A children's picture book about the goldfish pond at the pope's summer residence reveals a side of him few may know.

Every day while Pope Benedict XVI is on vacation at Castel Gandolfo south of Rome, he feeds the goldfish after praying by a nearby statue of Mary, tossing them pieces of bread.

The little-known factoid was revealed in "The Mystery of a Small Pond," published Tuesday amid great fanfare.

The pope's private secretary, Monsignor Georg Gaenswein, the heads of the Vatican Museums and Vatican publishing house, the author, and the caretaker of the pontifical villa spoke at the launch.

Gaenswein says the book reveals the "mystery" of Benedict, "who we all know is a great theologian with a powerful mind, but who has a very, very sensitive soul."