Was he eating F/T previously? You don't specify..
He's lost less than 40g, which isn't a lot IMO for a 1000g snake. I would keep offering once/week like you've been doing if it was my snake. I'm sure it's stressful, but he doesn't look too thin to me. If he continues to refuse and loses ~100g (total; 10% his body weight), I would offer a live mouse.
Reply With Quote