Blondielovesfish
Kia Ora
They probably won't breed but if they do, they will either eat the eggs or you get fry. The fry will either die, or, if you take care of them right, they will grow into adults and you can rehome them 
Actually, after some thinking. I think your fish would be happier if the Otocinclus weren't there and there were 7 Pygmy's. It would take some strain off your filter and will slightly under stock it. It will still look great though
*facepalm* Ignore the last post. You could have 10 Pygmies and a Betta.
Sorry, I was still thinking you were having a 10 gallon, not a 15.
Actually, after some thinking. I think your fish would be happier if the Otocinclus weren't there and there were 7 Pygmy's. It would take some strain off your filter and will slightly under stock it. It will still look great though
*facepalm* Ignore the last post. You could have 10 Pygmies and a Betta.
Sorry, I was still thinking you were having a 10 gallon, not a 15.