They get fed usually a F/T medium rat, in theory, once a week, but sometimes one of them won't want anything, or will only take a small rat or large mouse, or nothing at all.
I guess I should say I try to get them to eat a F/T medium rats every week. If they're still hungry, they get more, but usually Phantom will eat 2 every week, and Savage will eat 1 about every other week.
Sorry if that's confusing. When I got Phantom, he was being fed F/T baby quail, but that was way too expensive for me to keep up and too far to drive to get them, so it took a while to finally get him on rats.
EDIT- Not sure if it matters, but Phantom has gained about 300 grams from when I got him about 10 months ago, but he still looks scrawny. :/