Fishwives are women who are married to fish. The clue's in the name. They are therefore quite possibly shortsighted and most definitely poor judges of character.
Since fish generally open and close their mouths silently, perhaps eating the odd insect, they aren't great company. Thus do fishwives gossip to each other all day, until they are forced to make things up for fear of their conversation becoming repetitive. For this reason they are not to be trusted.
Need proof? Let's look at some fishwives' tales…
'I just bought a cabbage and it had arms and legs and it spoke to me.'
'Some people say that William Shakespeare didn't write all them plays and that's right. My husband, who is a chub, wrote them.'
'I wished I was dead, I really did. And then I was dead and then I came back to life and I was reincarnated as a squirrel. So the next time you see a squirrel, that's me. It is.'
'It's bad luck to take a banana on a fishing boat.
Why? Er. Because mischievous little people live in bananas and when night falls they peel the bananas and slaughter the crew with pickaxes, then burn the boat down.'
'So I said to Ethel, and then she said to me, and well I never did! And you wouldn't believe it! I know! Oooh, I've warned them before! I did, didn't I? I know! And did you see Cedric? He wasn't! He was! I know! Well, if ask me…' [YES, THAT'S ENOUGH FISHWIVES' TALES– ED.]