A Male Betta question?

I have a male crown tail betta and he is blowing a bubble nest right now....I do not have any females in the tank with him but I have 2 in a tank right next to him the tanks are touching each other....but the fish are minnows(mosqiuto fish) and I'm not aware if either are females(and im not sure if my male betta can smell the female minnow in heat.....lol I breed dogs not fish so please correct me if im wronge)Anyways why would he be doing this if their are no females in the tank with him also I watched videos on youtube and theirs had females in the tank with them so thats what made me start thinking about it. And I think it would be cool for my fish to have some babies so do I get a male mosqito fish and see if they breed(oh ,oh I found 4-6 bubbles in my mosuiqto fishes tank do they ddo the bubble deal also or what). I will read up on it if I decide to do it....Please any help will be greatly apprcialted. oh their are 2 minnow in the other tank and just one betta in the other tank they are the only fish I own. one minnow is 1/4'' the other is 1'' the betta is like 1 1/2'' without all the feathers/gills/whatevers