This is a repetition of the "First Egyptian Plague." Ex. 7:19-24. When the waters of Egypt were turned into blood all the fish died, but here nothing is said about the inhabitants of the rivers and ponds. Then John heard the "Angel of the Waters" say--"Thou art righteous, O Lord, which art, and wast, and shall be, because Thou hast judged thus. For they have shed the blood of saints and prophets, and Thou hast given them BLOOD TO DRINK; for they are worthy," or deserve it. As a confirmation of the saying of the "Angel of the Waters," John heard another voice come from the Altar, saying, "Even so, Lord God Almighty, true and righteous are Thy Judgments." Those will be awful times when there will be nothing but BLOOD to quench the thirst. The expression "Angel of the Waters," reveals the fact that even certain divisions of nature are controlled by angels.