I also wondered, it remember distinctly that during the Hokage battle (The first and the second hokage fighting the third) they said that only the first or the second could make water appear form nowhere. Creating water was a huge jutsu that the first or the second could only do.

As I don't seem to see any lake or river nearby and seeing that there's water coming from Kisame's mouth. Must mean he has mastered that jutsu?

EDIT: It was the second hokage who could do that.