Yes and no. I'll start with the no first. Geneticly they are incompatable. Any "successfull" mating will be deformed and very short lived. I had a Gold Saum spawn with a female Salvini and produce fry but with the afore mentioned results. Just doesn't work. As for the yes ,well they will most certainly try if they are each others only option . Problem is though that if you try to add another fish of the opposite sex even if the appropriate species since those fish have basicly decided to pair they will likely not accept the newcomer(s). You'd basicly have to seperate them to different tanks to break the bond .