You will need: 24 stairs of your choice, water buckets, 8 slabs of your choice, and some fish of your choice.
Step #1: build a four by four loop with you stairs. Next, make another loop right over the loop of stairs you just built. If this is too confusing look at the photo bellow.
Step #2: Fill the loops of stairs with slabs.
Step #3: Pour water buckets on the four slabs on the top to flow down to the bottom. Next, put some fish in, but dont put to many or they will push each other out.
That's it!!!! UwU