Your little frog is so cute! Looks just like a few of mine. Ok, I'm going to give you my opinion but you may not like it. Now, mind you, I am no expert, but since acquiring the 11 Gray tree frogs I am currently adopting into my family, I have spent hours and hours and hours researching them. So, here goes. First of all the tank you have him in is way too small-----I repeat---WAY TOO SMALL! These little fellas like to climb like crazy! Your tank should be no less than 24 inches tall (this is optimal). There are numerous ways you can go about acheiving this if you are short on funds, i.e.--kits to turn a 20 gallon fish tank into a terrarium (standing on it's end), put 2 20gallon tanks together, buy pre-fab ones from numerous dealers online, I think one of the companies is called Protean (I'm not endorsing them, just a suggestion from someone else that told me about them, always do research about a company first), and numerous other options. I think I read that you want to get more Gray's? If that is the case, I would invest in the 36x18x24 (in inches) exo terra, that is the biggest they make and would be ideal for a small family of frogs. If you are planing on keeping just the one frog then I think the medium one (18x18x24) would be sufficient, I believe the height on that is 24 inches too. That is probably one of his biggest stress problems right now. Also, I looked at your pictures and his water bowl is dirty. Mine DO NOT like a dirty water bowl. I clean it out every single day. What are you feeding? I have read that variety is the key to happiness. Although, he still looks young so fruit flies and pinhead crickets should be his staple diet until he gets older. Mine are 1 month old and do not get anything bigger than an 1/8 of an inch to eat. I have a few that are bright green without a pattern, a few that are light gray with spots, a few that are a dark gray with pattern, and one that is almost black. I have never read that there color depends on their mood so I can not give you any advice on that, but I will no doubt be researching that in the next few days. I have read that these guys are the chameleons of the frog world so I just assumed that they changed colors depending on their surroundings. I can't help you on the lighting issue as I am still researching that myself, but I did read that you should be very careful with lighting on small terrariums, it can be harmful if you don't do it right. There is a very educational care article on Gray's on this forum. If you haven't already read it, make sure you do, I think it talks about lighting. It's at the top left hand corner under frog and toad care articles. I can not stress enough how much these guys like to climb, and if they don't have that option they will be unhappy. These are arboreal creatures and after their first year of life they normally don't come out of the trees except to mate. This is just my opinion mixed in with what I have read from some experts. I hope it has helped.