There are numerous reasons why your gecko might refuse food, but stress is a leading culprit.
It can be scary when your pet doesn't want to eat, but when it comes to geckos, lack of appetite doesn't always mean illness. The gecko's life cycle, the time of year, and even stress can affect the appetite of a gecko, and it is important that owners recognize the signs of each so they can fix any potential problems.
Before you attribute your gecko's lack of appetite to stress there are a few things you need to rule out, and the most important of these is illness. Geckos with an infection, parasites, or metabolic bone disease will not want to eat.
Observe your gecko closely. Do you see any red or swollen areas (including his belly)? Are his eyes filmy? Is he breathing or walking abnormally?
If your gecko is showing any of these signs he may need to see a vet. If he isn't, it is time to consider the life cycle of your gecko as a possible culprit.
The appetite of a gecko varies throughout its life. Hatchlings never eat much in the first days of their lives, and juveniles eat a lot, but may slow their intake suddenly when their growth spurt stops.
Many geckos refuse food a day or two before they shed, and males often stop eating during breeding season. Some geckos are even sensitive to the changes in the seasons, and may show a decreased appetite during the fall and winter. If any of these things apply to your gecko, you may have your answer as to why he is not eating. If they don't, stress may be the issue.
First, check the temperature of your gecko's home. Improper temperatures, especially temperatures that are too low, can cause stress and a decreased appetite. You will need to research the ideal temperature for your specific breed of gecko, but for most geckos the tank temperature should be between 70 and 90 degrees Fahrenheit. If your tank's temperature falls within the recommended range already, you may need to consider things from your gecko's point of view.
Geckos can become stressed from any change in their environment. Transportation, a new home, and bullying by other geckos are some of the most common issues. If a newly-purchased gecko isn't eating, it is likely due to the stress of transportation and adjusting to a new home. While geckos can sometimes take weeks to become comfortable, they usually adjust on their own, and, in this situation, continuing to offer food is the best an owner can do.
If your gecko isn't new, but lives with other geckos, observe their behavior. A dominant gecko may be bullying a weaker gecko and causing it unnecessary stress. Sometimes it is obvious, and your gecko may have visible bite or scratch marks, but sometimes it is more covert. If another gecko is constantly crowding or chasing your gecko away from food or space, you may have found your problem. Separate the two geckos and watch the submissive gecko to see if it begins eating again, keeping in mind that it may take time for it to recover from the stress.
As always, the most important part of owning a gecko is to be observant. Next time your gecko stops eating, don't panic. Take time to observe, and then take the proper action. Their health and happiness will be your reward.