"The Rainbow Fish" and "Rainbow Fish and the Big Blue Whale" are delightful children's books by Marcus Pfister. Part of the Rainbow Fish series, these hardcover books published in 1998 by North-South Books, Incorporated feature beautiful illustrations and engaging stories. The books explore themes of friendship and marine life, making them a charming addition to any young reader's collection. With vibrant colors and captivating storytelling, these books are sure to entertain and educate children about the wonders of the sea.