My bugged eyed golfish is lying on bottom of tank

Question
The question I have is, why would our (black) bugged eyed goldfish be lying on the bottom of our fish tank? It eats some, don't move much, is also pretty fat. Could it be pregnant or sick. I have searched it for ick and missing scales and such , but have found nothing. I don't no how to sex them, one we have had longer than the other, the one laying on bottom if much bigger than our other, almost 1/4 to 1/2 bigger in size. Would you have any idea on this if so let me know thanks David.

                                               Krista  

Answer
is the fish breathing heavily??? What do you feed your fish?  Goldfish are very prone to intestinal blocks which are mostly caused by pellet food.  You can offer the sick fish frozen green peas (thawed out)or brine shrimp which should help the fish pass a blockage.  I would also have the water tested to make sure that the water chemistry is where is should be.  Please keep me posted.. dave