It's hard to tell gender in a young fish. I've had my baby for more than a month (although he looked younger when I got him than it looks like Shark was), and I'm still not 100% that he's a boy. But I think Shark is a Crowntail, because of the way the tip of his/her tail is serrated in the most recent picture.
Losing color can be a sign of stress. Is it possible that the tank is too cold? A 3 gallon would be harder to warm than a half gallon. If you haven't already, it would be good to buy a heater. Shark also looks bloated, so you might be feeding him a bit much.
My BettasDavros, multi-colored veiltail maleSpock, blue veiltail maleOswin, red veiltail femaleCastiel, blue and white Delta maleGandalf, marbled veiltail maleDr.Horrible, yellow veiltail male