I think that when a vagina has a scent other than just standard skin and sweat, that smell is most often characterized as 'fishy.' This isn't related to ovulation, just to the frequency and effectiveness of bathing, how effectively the underpants deal with sweat and/or urine, and probably also depending on diet. (If someone eats a lot of onions, for example, the smell of onions can come out in the sweat where the legs meet the crotch area quite strongly.) If you are noticing a smell in particular at ovulation time, it could be that the eggwhite cervical mucus related to ovulation happens to collect the bacteria in the region and make it more noticeable. Cervical mucus at other times in the cycle is not thick and sticky, and might not be as good at concentrating smells.
The smell most often mentioned in relation to a certain time in the woman's cycle is if the woman has bacterial vaginosis (BV), but it's right after the period, not mid-cycle, and it isn't called fishy, it's most often compared to the smell of rotting meat. The only other common bad-smell issue in relation to vaginas is when there is a forgotten tampon. But again, those smells are more in the dead-meat category, not just lightly fishy, and probably the smell of a forgotten tampon would not be cyclical.
Anyway, I'd say (from all the jokes that have been in the culture for generations about vaginas having a fishy smell) that it's probably perfectly normal. If you really dislike it, take an extra bath at that time of your cycle, and always wear plain cotton underwear. A mini-pad or pantiliner at that time (changed whenever you use the loo) would help keep things plain-smelling also. Do also keep in mind that it's probably nothing to be self-conscious about even if it happens. (Some guys love that smell. Napoleon once wrote to Josephine that he was coming home from whatever campaign he was on, with the instruction "Coming home -- don't wash.")