a black belly does exist it makes a yellow jacket when you pair it with a pastel they are super hard to get ahold of a friend of mine ownes one and paid over 3500 for it but doesent look like yours the black belly goes in a line down its belly i think you got a normal with a belly pattern unless you got it from a well known breeder all i can say breed it with a pastel and see what you get
^^^^This^^^^
I've only seen maybe 1-2 on fauna, and that was the price range ~$3500 or so.