Believe it or not, menstrual blood has no odor. Neither does sweat for that matter. But, let’s be real, we have all experienced a smell or felt less than clean down there. First, menstrual blood is made of both blood and tissue that sheds from the uterus. When menstrual blood mixes with our own bodies, bacteria and odor may develop. Many describe this as fishy. Just like when we sweat. Perspiration has no odor, mix that with our body’s bacteria and we all know what that odor smells like. Noticing a fishy odor is common, and very likely unnoticeable to anyone else. Think about it, have you ever been able to tell if someone is on their period? To decrease odor, change your pad frequently. Assure you are using the pad or tampon with the right amount of absorbency. If a fishy odor persists after your period is over, an infection such as bacterial vaginosis may be present. Contact your healthcare provider for an in-office examination.
Believe it or not, I have a friend who went to an all-girl high school and their mascot was the Tuna. Can you imagine the jokes those girls had to endure? There are all sorts of bad jokes about vaginas and fishy smells, but if you're concerned about your body, it's no laughing matter. Just be sure to change your pads or tampons regularly and wash your vulva (the external areas) with a mild soap and water when you bathe or take a shower; those simple measures will help control any natural odors. You should know that when you're not on your period, there may be a subtle odor as well. If the smell you're noticing is unusual for you — a stronger or distinctly different odor than what you normally experience — then it might be wise to bring up the question with your health professional.
As long as you're keeping yourself clean, you're the only one that can smell that. If you're really uncomfortable, try spraying some 'feminine deodorant' type product on the outside of your panties or inside of your pants (better than directly on your skin), and that should help" - Anony