Can you tell me about the set up?
UVB? Type coil or tube? How old?
Area to locate a Herp Vet?
Temps and how measured?
The UVB is not strong enough and it is also the coil type which can cause a Photo kerato conjunctivitis, which is like snow blindness and can cause the eyes to swell as and have discharge. I would change the UVB to a tube type to extend the length of the tank. A 10.0 would be the right size for that tank. As far as color, it can change with mood and temperature. If the temps are too cool, the WD will get darker to absorb heat. The green color is normal and usually means the Dragon is comfortable. I would have a Fecal done as all reptiles carry parasites and if stressed they can go into a full bloom. I am going to give you a site with a well known authority on water Dragons. It will give you information that you will not get from a pet shop from ailments and what to watch for to diet and complete care.
This is on the coil UVB:
compact UVB problems: http://www.uvguide.co.uk/phototherapyphosphor-info.htm
I can also locate a herp Vet for you with a State. Joan
27324 satisfied customers