My goldfish seems to be guarding the left front of my tank... If any of my cichlids come near, he chases them away, including the ones that are almost as big as he is. It chases away the other fish too (including ones bigger than him), but it seems to mainly focus on the cichlids. any idea why its like this? I know severums aren't exactly mean, but you would think an 8" severum would be able to stand its ground against a goldfish.