It looks like a male,but not sure if he/she has its fin pulled up or not
Here have a look on this thread,it shows a good indication of male & female livebearers
http/www.fishforums.net/index.php?/topic/317770-sexing-dalmatian-mollies-and-blue-fancy-guppies/
Which one does your dalmation fin look like? pointed fin or round fin in front of its anal fin?