I'm very confused on sexing a fh. . . . i have a zz rd thats about 4 inches from tale to lip, there is a little kok but not huge like most male fh's,, but there is a small tube looking thing that shows under the belly befor the anal fin. what is that ?. . . .. . can somebody please explain different ways of sexing a fh please. . . . . . thank you!