It was maintaining territory and keeping other fish away. It also was the first one to come to the surface of the water when I put my hand over the tank.
That was the dominant behaviour I think I exhibited (I'm no expert here) but it had also been in the tank much longer than any of the other GBRs. The other ones had been just added around a week ago but it had been in there for around a month. Could it just appear to be dominant because it was older (bigger) and had been in the tank longer?
Every male ram will attempt to be the dominant, but there are several factors in this. Within a given space, one of them will usually be on top. I'll come back to this momentarily. My previous post referred to your comment about dominance in the store tank. This is a near certainty that the fish is a male. Its interaction to the other rams is very indicative once you are familiar with this; males will continually challenge one another, while females will sort of just sit there. Very general, but obvious when you see it. The male(s) will allow one or sometimes more females to remain near them, and this indicates a likely bonding, so it is a fairly safe bet that this male and female will get along in your tank. Not every female will be accepted by a male, and vice versa.
Time in the tank is a factor too, as a male will establish his territory and this doesn't take long; once he has, other males will be driven from it, and some of the females might too. The territory size depends upon the aquascape; in a fairly open tank, the entire tank becomes "his" space. If the tank line of sight within is broken up by chunks of wood and plants, the space he defends may be smaller.
Returning to the hierarchy of males, I had an interesting experience with another species of dwarf cichlid many years ago. This is well documented in the literature within some species, but it was new to me back in the 1980's. I acquired a group of five wild-caught
Apistogramma bitaeniata [they were in those days named
A. kleei but later study changed this] which I assumed were four females and one male. The male was clearly so, and the other four behaved to me identically, and looked identical in appearance. The male spawned with one or two females. Some time later, he died. To my surpise, one of the "females" quickly developed the colour and fins of a male, and subsequently spawned with a female. This was not a case of sex change, but merely that of a male being subject to the dominant male in the hierarchy, and only when the dominant male was no longer present did the other male become dominant. I have subsequently learned that this characteristic is common to many apistos, perhaps all of them, but it demonstrates the importance of hierarchy within a given space. In nature of course, in most cases the males would spread out so this would be unlikely to occur like it does within the confines of an aquarium. The pheromones released by fish are a chemical signal to others in the species, so it is more than just mere sight.
Byron.