Mid-Autumn Festival isn't until Oct 4, but mooncake merchants are already battling for customers.

And the trend of diversifying flavors beyond the traditional sweet fillings packed inside flaky pastry discs continues.

Take the Shanghai First Food chain, which is offering three new varieties this year - pickled Chinese cabbage with bullfrog; abalone with fresh meat; and fresh meat with dried bamboo shoots. The bullfrog mooncakes are particularly popular. About 3,000 are sold online every day.