Aight, I get that OP is what you might call a repeat offender when it comes to posting things over and over. But the issue is still a significant one.
So, anyone scrolling through the responses here so far is going to see two main things said.
One, that it's hygiene, and/or that it's an "infection" (though that term isn't fully accurate).
There's more to the story than that.
Talking specifically about the "fishy" odor, not any of the others possible on human genitals (because it isn't just women that can have that particular odor), hygiene isn't usually the driving factor. It's typically going to be an imbalance in the microbiome of the genitals, particularly the vaginal canal, or the presence of an unfamiliar microbe.
Trichomoniasis, a condition caused by an invading protozoan, is usually going to be the cause of a strong, unpleasant rotten-fishy type of smell. It's also got other symptoms, but that's not the thrust of this. But it is absolutely not a hygiene issue. Doesn't matter what kind of routine you have, it isn't going to prevent it.
The less pungent "fishy" smells tend to be more about the usual assortment of microbes we all have on us at all times being disturbed enough that one or another is outcompeting the others. Bacterial vaginosis is what that's called. It isn't so much an infection as it is something going wacky. Now, this can be triggered by bacteria from a foreign source getting into the vagina, or even just onto the vagina in enough numbers that it throws things out of equilibrium. This may or may not be a result of sexual activity.
Again though, hygiene isn't a primary factor. If anything, people going nuts over washing or using shitty products is more likely to cause problems than just not bathing. You start screwing up the Ph of the genitals, and germs throw a rave. Lack of bathing doesn't tend to cause short term trouble, and even once enough oil and dead skin builds up to grow colonies in abundance, doesn't tend to get fishy as much as that cheesy, funky, slightly rotten smell. And, even then, if everything stays balanced, you might not have any excess odor, it's just that it's possible.
If a person is using conservative methods with their genitals, isn't fighting an active infection, and also isn't doing a lot of crazy shit, they can still have what might get called fishy, but really isn't what people think of. Our slime, be it boogers in our noses, rectal mucosa, vaginal fluids, or whatever tend to have a sort of meaty undertone. That protein smell is also kinda what fresh fish smells like if the fish isn't very oily. Think something like bream, maybe catfish, rather than tuna. That's just always there, underneath whatever personal variances there might be.
However, some personal variances do run closer to something like salmon or mahimahi. It isn't going to be super strong in most cases, though you do run into it occasionally. But it isn't an unpleasant scent, just very "meaty".
Also, I want to repeat that it isn't only vaginas an vulvae that carry these smells. Penises definitely can smell fishy. Don't forget that parts of the penis are mucous membranes too, so they'll produce the same basic range of aromas.
Since it often comes up, there are right and wrong ways to wash your junk. There are also ways that aren't necessarily wrong, but will give outcomes that aren't really desirable either.
The current best practices are the same ones I used for twenty years while washing other people's junk. I look them up any time I talk about this subject because there's always one asshole (at least) that wants to claim it's bullshit. But I was responsible for the skin health, including genital health, of hundreds of men and women, and it was a source of great pride that my patients never stank. If you factor in pediatrics cases, and cases where I wasn't a long term caregiver (subbing in for a weekend or whatever), that number gets into the thousand + range far enough I can't keep track.
There is the caveat that some medical issues may require a change to general best practices. If that's the case for anyone, consult whatever doctor/provider is guiding your care for your individual needs, this is all general purpose.
So, those best practices are to use no soap, minimum abrasion, and ideally only warm water (not hot). You don't need a washcloth, but definitely avoid anything that feels scratchy. Your bare hands and warm, running water are all it takes, period. Yes, even during one's period. Anything else is to satisfy ones mind, not cleanse the genitals, and that's okay if that's what you want.
But soap strips oils more than is ideal for genitals, and it dries out mucous membranes. This is a recipe for bacteria to set up a factory and go crazy. It is entirely possible to kick off a bacterial vaginosis issue from over zealous bathing, especially when soaps not well designed for genitals are used. There are soaps on the market that are designed to gently cleanse genitals.
The problem is figuring out which of those that claim to do the job right actually do. Most of the time, if in doubt, go to a medical supplies place and see what kind of perineal care products there are, compare ingredients with whatever you're wanting to buy that is available in a regular store, and be prepared to experiment with what does and doesn't help your skin.
The other big part is to rinse well and dry thoroughly. A lot of skin issues start with moisture hanging around. Most of the time, you can go out, get sweaty as hell, and not bathe, and still have zero issues if you dry yourself well along the way. Jock itch, as an example, doesn't come from being sweaty, it comes from staying damp. You can't always help that while out in the world, but you definitely can after your shower. If you're time crunched, a blow dryer on a warm or cool setting can get the job done.
I personally do use soap on occasion, if I've been doing something grimy enough that it's gotten everywhere. So it doesn't have to be fanatical. But overall, the less you fuck with your genitals' balance with soaps, scents, or anything else, the less trouble you'll have with unpleasant odors.