Growth and Feeding - Starvation

I don't know much about my little “foster” before he came to me – but I know that his first owner abandoned him and he went through a prolonged period of starvation as a result, so he's a skinny thing with short little gills. Then when her sister found him she had him for a week or so and fed him salamander flake food from the pet store, which he may or may not have eaten, she wasn't sure. Now that he's with me he's been getting earthworms mostly, I tried from liver and he couldn't figure out how to eat it and wouldn't intentionally touch bloodworm tablets. He's really all about the earthworms – but I worry I'm feeding too much. Given a chance he will eat 4-6 worms a day, which seems like a huge amount compared to what other people here feed and talk about in other threads. I worry because I don't want to feed him too much too fast coming out of starvation and cause internal problems (I don't even know if that happens with these guys, but it can with other animals so I'm not sure,) but I also want him to get everything he needs. I have no idea how old he is, but he's about 6.5 inches long.

Start with small meals once or twice a day, at least for a few days. After that, you can feed larger meals daily until he puts on weight.

Thank you!