Red tiger Oscar fish

Question
My boyfriends red tiger Oscar fish has been acting weird we have like a skull in there and most of the time she hides in it we think she's pregnant but were not for sure she seems lopsided when she swims she's kind of leaning to the side or if she's at the bottom just sitting there she's kind of leaned over as well. We feed her feeder fish she's not over fed at all. The tank is well maintained its a pretty big tank for her she's by herself in it besides when the feeder fish are in there with her were not even sure if its male or female. She generally swims in one area which is around the skull but she mostly hides in it she doesn't swim as fast and she only comes out mostly when the light on her tank is out she seems mostly active when the lights out. So how can we find what her sex is? Also what could be wrong with him/her?

Answer
Hi Courtney,
  First, please realize that oscars lay eggs so they cannot be pregnant as such. It is pretty much impossible to tell the sex of oscars because the males and females look exactly the same. You can only tell at the actual time when they are laying eggs because the female's spawning tube is differently shaped than that of the male (his tube is more pointy).  

 As for what is wrong, most likely the problem is an internal infection caused by eating feeder fish. I strongly discourage people from feeding feeder fish to cichlids such as oscars because all it takes is one infected feeder fish.

-- Ron C.
  rcoleman@cichlidresearch.com
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