Help with tiger salamander in metamorphosis

so I purchased a tiger larvae on ebay. Certainly WC. I got him on Friday and he was and still is active and looks healthy but he won't eat. On Friday he had big gills still but was gulping air. So I changed his setup from mostly water to half and half with easy access to get out and in of the water. Declorinated btw. I use coconut fiber enough for him to burrow. Its kept moist and the room varies in temp from low 60s at night to 72 73 during the day.

So on Saturday I saw saw his stripes starting to show up and his gills were noticeably smaller. Sunday his gills were little nubs and he was crawling out of the water. I never owned a salamander larvae before so I was surprised at how fast he changed. Really quite interesting.

So about the food I've been offering red wrigglers from the pet store and blood worms. Tried a cricket too but nothing. On Friday when I first got him a couple hours after I put him in his setup i offered a worm. He bit at it a few times but didn't eat it. I think it was too big as I did not cut it in half. But he has not touched any food since. Is it because he's in metamorphosis? Also he is only like 5 inches, I've seen water dogs a hell of a lot bigger than him that are still fully aquatic. Is it normal to morph when they are so small? Thanks for reading.