Why is my leopard gecko's tail thin & bearded dragon's chin black?

Have Mulan examined by your herp veterinarian. Tail rot can be caused by trauma or infection. If it severe enough, amputation may be necessary to prevent systemic infection. Stress can also cause body parts to turn black. Commonly, it is the "beard"/throat that turns black during stress or anger.

This color change is usually due to stress but could be due to other things as well such as improper temperature, diet, etc. I strongly suggest you review all your husbandry to make sure you are doing everything correctly. Refer to this link. ( https://www.lizards101.com/why-is-my-bearded-dragon-turning-black/ )

Thanks for reaching out about Leo. Hibernation is stimulated by winter conditions (cold temperature, decreased food opportunity). If the environmental temperature is still hot, concerns are that she is ill and a veterinary visit is recommended. Intestinal parasites or infections, metabolic disorders and other possibilities exist. Good luck.

Make sure any prey you feed is appropriately sized, no bigger than the space between his eyes. If he has any stuck shed, a good soak in a warm water bath for 15-20 minutes daily may help. If he is constipated, a gentle abdominal massage, from front to back, during the soak may stimulate defecation.

It's probably best to have a vet take a look at the tail especially if it is appearing injured or peeling. Do NOT apply over the counter medications to the area unless instructed by your vet as it may be toxic or deadly to your beardie if he were to lick it.

By "stick-tail" I'm assuming that you mean the tail has become skinny. This means that he has been losing weight over a long period of time. This usually happens because of a disease process or incorrect care. Since this has been happening for a long time, it's not an emergency, but it's definitely wise to visit the vet tomorrow. Without knowing what caused this, I cannot recommend anything in the short-term to make him feel better. I can only recommend that you ensure that he is being kept at the optimum temperature and environment. I've given a link below to a website that has great information about proper care of Leopard geckos. http://www.anapsid.org/leopardgek.html I hope this helps and Garbanzo gets better soon.

Iggy does not look underweight but i have nothing to compare the way he looked before so i can't tell you for sure regarding weight loss. as long as he is active and eating normally i would not be worried, unless you see that he is losing a lot of weight fast.