Strange cichlid behavior

Question
Hi!

I noticed one of my cichlids doing a very strange thing: It is burrowing out a hole in the gravel (down to the bottom glass) by picking up rocks with its mouth and spitting them off to the side.  It is also chasing away the other cichlid in the tank when it gets anywhere near this area.   Has been working on it all day and still is now as I type this.  Could the fish be pregnant?  There ARE 2 in the tank.  Can you tell the sex of a cichlid? One is very aggressive (the one doing the hole-digging) and the other is passive.  Could this one be pregnant?  There is no bulging belly or anything but I don't have much experience with cichlids.  Thanks!  

Answer
As there are many types of cichlid, unless I know the exact species, it is difficult to tell. Although, the symptoms you are describing could be pregnancy. Some fish grab pebbles or gravel and clean the gravel off them, and spit them back out.
If you tell me the species, I shall find out more for you.