we have a rio 180 and keep 10 cardinal tetra, 1 male betta, a male and female BN plec, and pinky the apple snail. we don't have any problems with the BNs and territory. we do have alot of good hiding places and two pieces of bog wood so this may be why but i don't think you would have any problems in a similar sized tank to mine. we have no problems with the bio load but we run an eheim 2128 filter in addition to the juwel filter.
Faye
Faye