Newly bought axolotl doesn't eat

I got this guy 4-5 days ago and for a fairly cheap price, but i saw my lfs put him and the other axolotl inside a 0.5g tank with half water. Its super cramp and there is no filter and bubbler at all. The other axolotl is really in a bad shape, unfortunately i cant buy both of them as i am tight on budget. But i am trying to save this guy, i offer bloodworm, ghost shrimp, fish or frozen prawn no luck at all. In my place its hard to find earthworm or blackworm. Water condition is perfect, all the ghost shrimp and live bearer are thriving and breeding like crazy atm. The temp will be on 18 celcius at night and 24 celcius in the afternoon

I have also tried tea bath and metalyne blue to cure the fungus infection. If anyone know how can i increase his appetite please let me know.