Hello Zeldor,
It would be a good idea to post some photos of your axie and the setup as they provide a lot of vital clues.
There are many reasons why an axie is inappetant. Firstly we need to determine if the axie is inappetant or is actually normal. Full grown adult axies do not need to be fed as frequently as juveniles or larvae. If you have an adult axie, it may just have its normal 'not eating everyday' appetite.
Stress can cause an axie to become inappetant. If you just acquired your axie, the new tank environment can stress it and cause it to not feed. However, give it some time to adjust and very soon it would feed normally once it has accustomed to its surroundings.
It is also important at this point to ensure the tank set up you have is not contributing to stress. Most importantly, monitor the water parameters, temperature and current.
The water should ideally be cool around 16-18 degree celsius. Anything above 22 i would consider stressful especially if prolonged. If this is the case, you would need to try cool down your tank. Here are some methods.
http://www.caudata.org/cc/articles/cooling.shtml
There should not be excessive water current flow in the tank. If you have a filter or airstone ensure that the water is not too turbulent by diffusing the filter outlet source against the tank glass or use a spray bar etc. You can also turn down your air pump settings or 'loosely' kink the tubing.
Invest in a colourimetric solution test kit if you have not done so. This is one of the most important thing you need in axie care. You would need to perform regular water chemistry checks. Your water should read 0 ammonia, 0 nitrites and <60 nitrates if your tank is fully cycled, and provided you perform 20% water changes regularly. pH is less critical but neutral around 7 is always safer. Use clean dechlorinated water for water changes. You can get a dechlorinator from most pet shops. Dechlorinators get rid of chlorine, chloramines and heavy metals in the water in general, making it safe for axies and for beneficial bacteria in your tank to thrive. You can read up on cycling and water chemistry here.
http://www.caudata.org/cc/articles/cyclingEDK.shtml
http://www.caudata.org/cc/articles/waterquality.shtml
Check that your tank has suitable hiding places like pipes, logs, pots, caves etc. Ideally 2 hiding places per axie. You can keep axolotls with other axies of similar size and can also use suitable feeder fish like guppies, minnows, platys etc. after a 60 day quarantine. Otherwise, you should not keep your axie with other species such as aggressive fish that can harm your axie. Axies suit bare bottomed tanks or using freshwater sand as substrate. Gravel or pebbles are not suitable as axies can swallow them and cause an impaction, which will cause illness or death.
Monitor your axie for other signs of illness or stress. Check for things like forward facing gills, curled tail tip, wounds, sores or growths on the skin and gills and odd behavior like darting about.
Hopefully you don't see any of those signs!.
Cheers
