Axolotl not eating

[wremmrg]

I have three axolotls in a 55 gallon tank with a plex penn 700 external canister filter. Three days one of my axolotls (Ghostie) stopped eating. The other two continue to eat fine. Water temp is 65 degrees Farhenheit, PH 7.6, ammonia 0, nitrites 0, nitrates ~20. Only change is I added an aquarium chiller last Thursday. Not sure if that is causing an issue, or if maybe its something I am not aware of, or if this is normal.

 

[wremmrg]

UPDATE: now the other two are not eating. Obviously something is wrong. Could really use some help. Gnostic did eat a part of a night crawler two nights ago, and small bites of frozen bloodworms last night. Sammy did not eat two days ago or yesterday, but ate a small piece of night crawler today. Clementine did not eat today. It is normal for clementine to not eat much, but both Sammy and Ghostie were pigs about food until now. Is it normal for axolotls to go days with out eating or suddenly decide to eat a whole lot less?

 

[Hayleyy]

Sometimes they can go off their food. All your results sound fine. Can you attach pictures of them?