What it a corydoras mating behavior??

I have 4 corydoras 3 of which are albino and 1 is leapard. I had just the leapard and the one albino and today I added the other two and the one albino is just pestering the new one. He doesnt hurt it and doesnt even bother the other one. He just ignores it my question is can the new one he is pestering be a female?? I cant tell the difference. If so what type of breeding area do they need and how large? I have tanks of all sizes so it will not matter if its anything under 55 gallon.....What type of surroundings do they need ? (cave, plants just gravel)??I only breed livebearers and never thought about this part because I have never had this type of behavior with them......I have only had corys a few times. I gave away my other two to a friend who needed them......