Bacterial vaginosis This infection is caused by an overgrowth of bacteria in the vagina. Symptoms may include a strong, fishy odor and a thin. If your odor is not fishy or yeasty and you have no uncomfortable symptoms (discharge, itch or irritation), your vaginal odor is most likely to be normal. All women. Bacteria present in the vagina may convert the TMAO to TMA, and the smell of fish occurs in vaginal secretions. Cruden and Galask (). What conditions cause vaginal malodour? · Bacterial vaginosis (the most common reason for genital malodour, a fishy smell) · Trichomoniasis (this is foul-smelling.