plz help me with 2 piranha spices

[Piranhas_collector]

hi,
i have 2 aquariums,in the first one i have 4 Pygocentrus Piraya (red belly pirahnas) 3" to 5" each, in the second one i have 3 "Serrasalmus Brandti", some people call it silver piranha here(i am not sure about that local name) one of them is 2", th second one is about 3" and the third one is about 5-6", anyway i am setting a new big aquarium and thinking about joining the heros from both aquariums together but i am afraid that some group will eat the other (brandti looks stronger to me), anyone may help,
i though first to put one red belly with 2 brandti and 1 brandti with 3 red bellys to test,
any information experts? please help!Thanks

[William]

I know that some people mix piranhas species without any problems but it is always a gamble. I'd say try it out and watch it carefully for any problems that may arise.

The size might be a problem a 2 inch fish with a 5 inch one. But that might not be a problem if the Brandti is stronger.

I would recommend making your test with all your fish simple when you have time to watch them for a few hours simple because adding the others later can create new group dynamics, power struggles etc.