Question: How can I save this Axolotl?

[Backkarurosu]

Hi, I'm new here, and I got a problem with my Golden Axolotl.
He is very thin, has very small gills and has a hard time eating, I don't know what to do.
If you could give me a hand I will appreciate any help given!

 

[keiko]

Please post your water parameters (ammonia, nitrite, nitrate, pH) and temperature. How often do you change the water, how much, do you use any water conditioners? What are you feeding your axie and how often? How old and long is the axie? How long have you had the axie? A picture of the axie as well as your tank might help too.

 

[Backkarurosu]

All the parameters of the water are Ok, I think i was giving him big parts of fish, so I am now reducing the size of the food, and giving him more often but tinier.
I will try to post a pic of him when I go home, so you can tell me if he is good or how he should be.
Thanks