Question: What is a typical belly shape ?

[snowbutton]

I don't know if this is normal for all ages of axolotl, but whenever mine ( about two inches long ) eats his worms, his belly gets a little bigger and darker, and sort of caves in in the middle. Since I just got him two weeks ago, he did not settle down and start eating normally until maybe last week, so I suspect that he got quite skinny and is adjusting to daily food.

 

[LoriML]

Perfectly normal. The belly looks darker as then are younger and the skin is thinner and more translucent. It becomes less obvious as they get older.