Jonah was swallowed by a creature called "The Great Fish" which is not just any fish. "The Great Fish" is a predecessor to Krishna in Hinduism. He saves Noah by pushing his boat to Mt. Ararat and then turning into the gigantic 8 headed cobra form ~ which he uses as arm/ropes to tie the boat to the mountain so it's not crashed and dashed to pieces.
"The Great Fish" also occurs in Sumerian, and later Babylonian religious stories and symbolism.
Oh, one more, Jesus himself is thought by some to be "The Great Fish", hence one of the reasons for using the Fish symbol in early Christianity. Yet others argue that Jesus manifest himself inside the fiery furnace where Mishak, Shadrak and Abendego were being burned. (No doubt this later experience was used to justify Friday afternoon fishfries).
On the other hand there may well be GIANT FISH roving around the world and they catch people. We just don't see them often ~ maybe no more than every 3 or 4,000 years!