oscar fish pregnancy

Question
I have recently acquired 2 large fish, I was told by the previous owner that they are oscars. one fish is larger than the other, both sizable fish. I don't know if they are male or female. The larger of the fish is slate gray colored. I've noticed lately that the under belly, around front fin area turns blood red, and becomes engorged. This particular fish is also very aggressive towards the other fish,which is orange in color. it will nip and nudge it quite often. also they both pick up gravel from the bottom of the tank and spit it out, leaving the area clear. what could possibly be going on?

Answer
Hi Brenda,
 They could be cichlids.  An oscar is one type of cichlid.  However, cichlids do not get pregnant as such, they are egg layers.  If you send me a photo of the fish to the address below I might be able to tell what you have.  

-- Ron C.
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidreseach.com>