He should be fine. They can go without food for as long as two weeks but it would be better if you can arrange someone to feed him even once over that time.
Make sure you do a water change before you leave. You can drop a few baby snails in there (not right in front of him though) for him to hunt and hopefully that'll last a couple of days. I drop nearly hatching snail eggs and baby snails for them when I go away for a week.
If you have other inhabitants with him, then expect some nipping when he goes hungry. At least that's what happened to my amano shrimps when I was away (two weeks) for the first time.