I have Dorados and Byrcons. I like Brycons better because at least they can live together in one tank. When I added one Dorado with my Brycons, the Dorado was going to wipe out and kill all my Brycons. The Dorado was then transferred out.
For that kind of traveling the fish would have to be a very cheap ST Datnoid.Red_Belly_Pacu,was there much size difference in the b's and d's when they were in your tank together?