female, espically if her belly is orange. The fins are a little different too, but a verbal description is not very helpful. If you saw a male and female in person or in photo, you would notice the different finnage.
THe males also have orange spots on their sides as well when younger. THe females spots will be really bright and their fins will have hints of blue and other colors that are faint. I had a male since it was about 1 inch long and it had spots but they are long gone. I just recently bought another one that was really colorful not knowing the sex difference and they both get a long great. I think I might have a breeding pair here shortly.
On the topic of convicts though. I see pictures of other convicts and their colours are very bold. My convict is not very black and white and hasn't been since I brought him home a month ago. The water conditions are fine. He was always being nipped by my JD but I moved him to a tank of his own. He digs like crazy and shows no signs of ilness. There's a background at the back of the tank. Is there something else wrong?