Was Jonah swallowed by a fish or a whale?

Was Jonah swallowed by a fish or a whale?
Jonah was swallowed by a big fish.	Jonah was swallowed by a whale.
Jonah 1:17 Now the Lord had prepared a great fish to swallow up Jonah.	Matthew 12:40 For as Jonah was three days and three nights in the whale's belly.

Christian Responses: Waterrock; LookingUntoJesus.net; Annotated Skeptic's Annotated Bible: Because he had done these things on the Sabbath day (Matthew 12)