My green tree frog is suddenly skinny and light green. What to do?

I would be concerned about a possible parasites. I would recommend taking him to a vet for a good exam and fecal screen. If he has parasites that could cause him to be on the skinny side. However if he does not have parasites it is important to look for underlying disease like infection, viral or even organ disease.

Check the water quality and temperature. Frogs are very sensitive to poor water quality. Low temps can affect appetite and activity. You may need to perform a water change and increase filtration. Discoloration may be due to poor water quality or infection. If the water changes do not help, consider an exam with your veterinarian or a vet experienced in treating reptiles and amphibians.

Check humidity and temperature in the enclosure. Either can affect activity, appetite and digestion. Soak him in a warm solution of water and unflavored PediaLyte. A gentle abdominal massage during the soak may stimulate defecation. Be sure to use dechlorinated (or otherwise conditioned) water for the soak. You will need to see your veterinarian or a vet experienced in treating amphibians if the appetite does not return.

Submit a stool sample to your veterinarian to diagnose intestinal parasites. Consider a supplement such as Oxbow Critical Care or Fluker's Repta-Boost. Review her diet with your veterinarian to make sure it is appropriate, adequate and that Saphira isn't getting too much vitamin D3 which can be toxic in large quantities.

Have him examined by your veterinarian or an experienced herp vet to diagnose and treat any infection related to the loss of the tail. In the meantime, increase tank temps by about 5-10 degrees F, soak daily in a warm 50/50 solution of water and unflavored PediaLyte for 20 minutes. Once he warms up and rehydrates, offer appropriately sized prey. Gutload prey for 24 hours prior to offering to maximize nutritional value. Supplement with a product such as Fluker's Repti-Boost to get weight back on him. You can clean the stump with diluted betadine or chlorhexidine. Use paper towels for substrate until the stump is healed.

Clean and sanitize the tank. Replace ALL the substrate with fresh organic topsoil or coco fiber. Do not use vermiculite or perlite. Avoid gravel, sand or wood chips. Ideal temperature ranges between 68F and 78F with the cooler end reserved for nighttime. Mist the cage several times weekly to maintain humidity. Provide a water bowl and clean it daily. Soak him in a tepid (75F) 50/50 solution of water and unflavored PediaLyte. This will provide warmth and hydration. A cold frog will not eat. Afterwards, offer live food. Something with a lot of movement like nightcrawlers or mealworms. If he still doesn't eat, have him examined by your veterinarian or a vet experienced in treating reptiles and amphibians.

Submit a stool sample to your veterinarian to diagnose intestinal parasites. Offer fresh crested gecko diet daily. Repashy or Pangea are brands I recommend. You can also offer appropriately sized prey (crickets, dubia roaches, mealworms, etc). Be sure to gut load them for 24 hours prior to offering to maximize nutritional value. Confirm proper environmental parameters. Low temps can affect appetite and digestion in reptiles.