My best guess would be female, from the markings. It also appears to have a hefty abdomen, usually seen on females. And the finnage is relatively short. Big for a young female, but that could be due to good care and a lack of competition for food.
Yes, he/she certainly gets a lot of food, and the only one in the tank. Two large water changes a week, because he/she is messy and I like doing water changes for the endless benefits. You were the one who told me male, granted, that was about 6 inches ago and it looked very different. I got some more pictures, by fair the easiest fish to take pictures of lol. One of them you can see the breeding tube.
Well, between the vent image and some double checking against other photos, I'm going to reverse myself (again!) and say that it does seem to be male. The pointy little vent tube certainly seems to indicate that. Isolated males usually get more extensive finnage, and a more elongate body shape, but the tube certainly tells the tale.