YOU SAID:
Yellow fish is swimming on the yellow pool.
INTO JAPANESE
黄色い魚が黄色いプールで泳いでいます。
BACK INTO ENGLISH
Yellow fish are swimming in the yellow pool.
INTO JAPANESE
黄色い魚が黄色いプールで泳いでいます。
BACK INTO ENGLISH
Yellow fish are swimming in the yellow pool.
That didn't even make that much sense in English.