What are your water parameters like. You may need very soft and acidic water conditions for them to breed. I'm pretty sure the Atabapo river, is a black water river. At least it look like one from some of the pics I've seen. If that's the case you may have to simulate its conditions in order to get them to breed.
You can always use a piece of egg crate to keep the separate until they get used to each other. I also agree keep them alone.
You can always use a piece of egg crate to keep the separate until they get used to each other. I also agree keep them alone.


