Get your self a real Bible:
Genesis 6:17
And, behold, I, even I, do bring a flood of waters upon the earth, to destroy all flesh, wherein is the breath of life, from under heaven; and every thing that is in the earth shall die.
OK? - All flesh - everything that is in the Earth shall die.
There were no exceptions, all animate life was corrupted and had to die.
I have enough. I look at the RC bible as inferior to the other translations! I have studied both scholastically and individually. I have 18 REAL Bibles, including Greek and Hebrew. I have no Latin version, as it is not an accurate rendition of the latter two I mentioned. You haven't confirmed anything, with your Douay-Rheims. It does not say anything about sea creatures being in the Ark. It specifies the creatures that lived on or above the Earth. The Hebrew indicates ON the earth, the DRY land!
Do fish "breathe"? Did God start over with creation? Inquiring minds want to know!
One theory about the fish, from ICR, gives plausible answers..