YOU SAID:

my fish died so i flushed it when i went to the bathroom

INTO JAPANESE

私の魚は死んだので、私はトイレに行ったときにそれを洗い流した

BACK INTO ENGLISH

My fish is dead, so I washed it off when I went to the bathroom.

INTO JAPANESE

魚は死んでいるので、トイレに行った時に洗い流しました。

BACK INTO ENGLISH

The fish are dead, so I washed them off when I went to the bathroom.

INTO JAPANESE

魚は死んでいるので、トイレに行ったときに洗い流しました。

BACK INTO ENGLISH

The fish are dead, so I washed them off when I went to the bathroom.