So Long, and Thanks for All the Fish

So Long, and Thanks for All the Fish is the fourth book of the Hitchhiker's Guide to the Galaxy sequence by Douglas Adams, published in 1984.

The title comes from the message the dolphins left behind when they left Earth immediately before its demolition for a hyperspace bypass, an event described in the first book of the series. That the joke is carried forward into the title of the fourth volume indicates how the sequence treats continuity: it is held together by running references rather than by a single continuing plot. The book opens with Arthur Dent being set down in what appears to be England, although he had watched the planet destroyed, and he has been away for years while only a few months have passed at home. He falls in with a man named Russell and Russell's sister Fenchurch, and the novel's business is his attempt to settle back into a life the earlier books had removed from him.

The book was later gathered with the others into collected editions including The Hitch Hiker's Guide to the Galaxy: A Trilogy in Four Parts and The More Than Complete Hitchhiker's Guide, which is how many readers have encountered it. Adams continued the series afterwards with Mostly Harmless.