So when Hugh Wilson wrote this episode, perhaps figuring that this would be the last (since the show wasn't doing well), he wrote it -- or parts of it -- as a sort of parody of the kind of show he felt CBS was asking for, a broad farce with silly costumes, pratfalls, and contrived explanations. He disliked the finished product enough to take his name off it and use the pseudonym "Raoul Plager" instead.
The show was placed on hiatus before the episode could air; when it came back, with a run of episodes that struck the right balance between what CBS wanted and what Wilson wanted, "Fish Story" was not shown. It was finally burned off at the end of May, when the regular season was already over. But it got excellent ratings in the show's new post-M*A*S*H slot, and has always been one of the most popular episodes, because it's just funny. Though the best part of the episode is not the main story but the B story, which is a little less broad because it's based on a real radio thing (DJs really do these drunk-driving tests on the air; this just asks what would happen if someone's reflexes got better rather than worse).
The Hulu/DVD version strips out all the music; this version puts it all back in: "Drinkin' Wine Spo-Dee-O-Dee" by Jerry Lee Lewis, "I'm Torn Down" by Freddie King, "Blue Collar Man" by Styx, "Alabama Song" (aka "Whiskey Bar") and "Light My Fire" by the Doors.
Cold Opening and Act 1
Act 2 and Tag