Adult discus could go a week without eating. I would feed them very well the week before, and do a water change as close as possible to your departure, keep the tank lights off if possible (don't know if you have live plants or not) and they'll be pretty inactive for the week. But as msjinkzd says, would it be possible to have someone, a close friend or relative, step in say just twice during that week to feed them a small amount of food? That's what I would do. If it is an inexperienced person, you can premeasure the food out for them, that way no overfeeding. Put a sticky on the tank of what the normal tank temp is and just have them check that the temps holding, and the last thing I'd do is let them know how many discus are in the tank and do a headcount when they come to feed. If an adult discus happens to die, the ammonia levels will probably go through the roof if the body isn't taken out. Even an inexperienced fish watcher could scoop out a dead fish with no instructions. I do not trust auto feeders. Read too many horror stories when they malfunction when people are away from the house.