I think this is a common problem....just like there are also women that don't like to perform BJs on their husbands. I think that most people actually enjoy giving or receiving oral sex, but there are a few that don't and some probably do it to make their partner happy and then some don't do it at all. I think that your partner never really liked performing oral sex to begin with..... He's being rude to you by comparing the vagina to fish or oysters... I think this issue needs to be discussed further with him and let him know that you're willing to leave him if he's not willing to do it, if it means that much to you. I know it would for me.
If you decide to leave him, please ask your future partner if he's willing to please you in that area and how much it means to you. Get it out in the opne from the beginning.