YOU SAID:
I heard the emperor is a fish
INTO JAPANESE
皇帝は魚だと聞いた
BACK INTO ENGLISH
I heard the Emperor was a fish.
INTO JAPANESE
天皇は魚だと聞きました。
BACK INTO ENGLISH
I heard that the Emperor was a fish.
INTO JAPANESE
天皇は魚だと聞きました。
BACK INTO ENGLISH
I heard that the Emperor was a fish.
That didn't even make that much sense in English.