What does Shakespeare mean by the word minnow?

A minnow is a small freshwater fish, typically of the family Cyprinidae, such as the common minnow (Phoxinus phoxinus). Shakespeare uses the word "minnow" in several of his plays, often in a figurative sense to refer to something small or insignificant. For example, in "Henry IV, Part 1", Falstaff says, "I am not only witty in myself, but the cause that wit is in other men. I do here walk before thee like a sow that hath overwhelmed all her litter but one. If the Prince put thee into my service for any thing, save to stale his horses and make 'em look thin, and dry them, count me the most horrible minnow that ever lived." In this passage, Falstaff is comparing himself to a sow that has lost all her piglets except for one, and he is saying that if the Prince puts him into service for anything other than to make his horses look thin and dry, he should be considered the most insignificant person imaginable.