I knew it was normal for them to drop some weight, but when he dropped 7.4 grams in a week I was determined to get him to eat something. I tried feeding him f/t twice, a couple days apart. I thawed them in the fridge for a couple hours and then warmed them through the hot-water-submersion-in-a-Ziploc method and wiggled them around a little. He wouldn't even smell them. He just wasn't interested at all.

On the other hand, once it was where he could see it, it didn't take him even 2 seconds to strike the live one. Now that I know what it looks like when he actually wants to eat I think I'm more comfortable trying to switch him.

It's good to know that 7.4 grams isn't as much as it sounds like when switching such a small little guy over, though. Thanks for the info, and thank you both for the compliments!