You certainly don't want two male Chinese water dragons duking it out in the same enclosure, and trying to breed two females or two males isn't going to give you baby dragons anytime soon. Luckily, once they reach a certain size, the physical differences between male and female dragons become apparent.
Chinese water dragons have a nuchal crest and a mid-sagittal crest. Look at your green pal and you'll see a ridge of spikes that extends from the base of his neck to the base of his head. That's the nuchal crest. Immediately below that you'll see another ridge with spikes that spans the length of his back and runs down his tail, known as the mid-sagittal crest. Both males and females have these crests, but males have significantly more defined crests that are larger and more noticeable. Males also have noticeably larger spikes.
Jowls and Head
Take a peek at your Chinese water dragon's head. A female's head is on the petite side, while males sport longer, broader and all-around larger heads. Drop your eyes a smidgen and focus on your dragon's jowls. If your pal is really a guy dragon, he'll have larger, puffier jowls with longer spikes. Females have jowls too, but they're considerably less noticeable, and the spikes on their jowls often look like nubs.
Femoral pores are glands that both female and male Chinese water dragons have. They're on the insides of your dragon's back legs, around his thighs. The pores show up as rows of brownish-black dots. They're larger and clearly noticeable in males, but less so in females. To see them, you'll need to handle your dragon and gently turn him over while he's in your hand.
For the most part, male and female Chinese water dragons show off similar colors, which range from dark to light green. But the Smithsonian Institution National Zoological Park points out that the color of a male dragon's throat ranges from bright yellow to orange. A pinkish color often extends around the bottom edges of their mouths. Those colors are nonexistent in females.
When to Identify
Forget about trying to sex your dragon if he's a youngster. ReptileChannel.com notes that until Chinese water dragons reach roughly 14 to 16 inches in length, they all look like females. Once they grow up a little, the changes—from the appearance of their crests to the size of their jowls—begin in males and make it fairly evident what gender your dragon is.