Prior to Polonius's greeting of Hamlet, he has spoken with King Claudius and Queen Gertrude about Hamlet's madness, contending that Hamlet's letter to his daughter Ophelia is evidence of the prince's mental imbalance.
This, in obedience, hath my daughter shown me;
And more above, hath his solicitings,
As they fell out by time, by means, and place,
All given to mine ear. (2.2.130-133)
Polonius has had his daughter show him this letter, and he has instructed her to have a contrived conversation with Hamlet to which he and Claudius will secretly listen.
At such a time I'll loose my daughter to him.
Be you and I behind an arras then;
Mark the encounter. (2.2.174-176)
Then, Polonius encounters Hamlet and greets him as Hamlet seems surprised.
Do you know me, my lord?
Excellent well. You are a fishmonger.
While literal meaning of fishmonger is one who sells fish, the word connotes other meanings:
- Those who sold fish were of the lower class and loud and loquacious, so Hamlet insults the courtier Polonius, suggesting that he is one who trades in a cheap way with frivolous words.
- In the Elizabethan age, a fishmonger had the connotation of a panderer, or procurer, one who used women for profit. Here, the father exploits his daughter Ophelia in order to procure information about Hamlet, instructing her to lure Hamlet to place where he will be hidden.
Clearly, Hamlet is aware of Polonius's chicanery as well as his exploitation of his daughter as, when Polonius exits, Hamlet exclaims, "These tedious old fools!"
Hamlet's first reason for calling Polonius a fishmonger is probably to make the old man think he is insane--i.e. that he really doesn't recognize him but thinks he is a complete stranger. Hamlet could have chosen any other name to call Polonius, but the idea of the old man being a fishmonger appealed to Hamlet's weird sense of humor. Polonius is like a fishmonger in that he seems to be popping up everywhere, that he is a nuisance, and that he is about as welcome as someone who smells of fish. Calling this distinguished elderly gentleman a fishmonger must have gotten a big laugh out of Shakespeare's audience, and it probably still gets a laugh out of contemporary audiences, especially because of the startled reaction it gets from Polonius. We like Hamlet because, for one thing, he has a good sense of humor. Polonius has no sense of humor at all. The old courtier goes around picking up tidbits of information which he can report to the king. The old man trades in information just as a fishmonger trades in fish. Polonius is getting old. At one time he may have been more useful as a counselor, but his mind has become weak. The best he can do not is to act as a spy and a talebearer. Like a fishmonger, Polonius has a lowly function and a lowly status. He is no longer of much use to Claudius. Hamlet despises him. He enjoys insulting Polonius to his face--which he is able to do because Polonius is already sure the Prince is insane. Polonius would dearly love to find out what is really going on inside Hamlet's mind. He is making a terrible nuisance of himself by interfering in Hamlet's life on the King's behalf. Hamlet reveals his resentment by choosing to call Polonius a fishmonger when he could have called him something a little less demeaning.