Arash, this is difficult. Discus are often choosy about their partners. Unless you consult a discus breeder to help you with picking the males, you might just end up with another female or constant bickerings instead. Your lfs is not going to be of any help anyway so it's best to try searching for discus breeders in your area and ask for their help.
If there is a male in the tank he may be sterile or hopefully not mature enough yet to provide viable sperm. Some hybrid discus are indeed sterile. This is good, at times, unless one is trying to generate a new variety. Discus are particular about choosing a mate, but like most other animals, will make do when pickings are slim.
forum community dedicated to tropical fish owners and enthusiasts. Come join the discussion about species,breeding, health, behavior, aquariums, adopting, care, classifieds, and more! Open to fish, plants and reptiles living in freshwater or saltwater environments.