usually by the time silver aro's are 12" they can hold their own with any size cichla.
i've never had a problem with cichla vs. arowanas except my 2 wild caught aro's tormented one of the cichla till he starved himself to death. but they don't bother the other 3 cichla in the tank.
my big aro and my original ocellaris, Dozer, were best buddies all of Dozer's life. they were never separate and they defended each other when there was trouble in the tank. my big aro still lives with cichla, just different ones now that Dozer is gone.
i've never had a problem with cichla vs. arowanas except my 2 wild caught aro's tormented one of the cichla till he starved himself to death. but they don't bother the other 3 cichla in the tank.
my big aro and my original ocellaris, Dozer, were best buddies all of Dozer's life. they were never separate and they defended each other when there was trouble in the tank. my big aro still lives with cichla, just different ones now that Dozer is gone.