I feed her daily and keep the diet as varied as I can. Day one she eats a whole nightcrawler. The next day it's a lighter meal of usually 2-3 small sinking pellets. Then it's a day where she gets either a wiggler from my redworm farm or a superworm. Repeat. Maybe you just haven't found the right food for your buddy. Experiment a bit and see what he likes. They also love wax worms and cricket.

What do you feed that very large axolotl? I've had my guy for almost six months now and he just doesn't eat enough. 

He'll eat a whole nightcrawler if I cut it in two and hand feed it to him, but thats once every three days. He just doesn't show the motivation to eat more than that.

It's wild what only 10 months can do