well given that ur jag is a nice size already. i would get a female of at least a teenager. meaning at least half full grown. you will have a VERY hard time getting him to "like" a super small girl.
to answer your question breeding them. the chances would be purty high that they will breed, given enough time to court.
however keep in mind that the manaconda isn't a very popular fish, IMO. success at selling them would be hard i think, but given that ur male is totally a shocker. ppl will prolly like to have some, including me, but i live across the huge pond from ya.
