I think it's probably female. It has the look and body shape of a female. The lack of yellow on the belly is not always a good indication of sex, especially with age and developement. My current two females at 2 1/2 yrs. of age already have virtually no yellow on their belly anymore. I have had many 5 yr. old + females that had absolutely no yellow left on their belly, whatsoever. Look at these pics of my two females ----- very difficult to make out any yellow on their belly from these pictures.
Female 1 in aggressive colors:
Female 2 out of the water measured at 4 3/8":
Female 1 in background behind male con:
Female 1 at left and female 2 at right with 'pink' con male:
Female 1 in aggressive colors:
Female 2 out of the water measured at 4 3/8":
Female 1 in background behind male con:
Female 1 at left and female 2 at right with 'pink' con male: