There are many problems with the story of Noah and his Ark. Here are a couple.

1. There are thousands of freshwater fish species in the world. For the Ark to carry all those fresh water fish, he would have to put each of the species in separate well aerated aquaria. I wonder where Noah could get those aquaria back in those days?? Would the fish survive the raging salt water seas for 40 days?

2. When the Ark finally lands, the marsupial mammal species would need jump off first then travel quickly to the Indian Ocean while being chased by placental carnivores biting them at their rears. Then the marsupials would have to swim all the way from the shores of India to Australia and that includes not only Kangaroos, but also Koala Bears, marsupial moles, marsupial mice, and wombats not normally found in water.

Just think how cozy it would be for sheep, deer, and rabbits to sleep with Afican Lions, Leopards and Jaguars for 40 nights!

There are also many problems of the geological type for such a massive flood to occur that  are not mentioned here.

(See Noah's Ark by Douglas Futuyma, PhD)