My female ornate (13") is a pushover, often getting bullied by male senegal (7"). It's all luck when it comes down to how aggressive yours might be. A 150 (6x1.5x2.5ft) gallon is no better than a 125(6x1.5x1.6ft) gallon for polys, as they need a larger tank footprint rather than a deep tank. All they are gonna do is either sit in one place or swim against one side of the tank.