Well, not to go against HN1, I'm sure he knows tons more than I do. But, I have an auto feeder that I used to use on one of my tanks when I was still living with my parents. I have my roommate to take care of my babies now when I'm gone. Anyway, I got this one Walmart.com: Penn-Plax: Battery Powered Automatic Fish Feeder,: Fish
If you get one, set it up like a week before you go to make sure the thing is actually working and it's the right amount for your fish. It goes twice a day, so I would put it on the smallest amount. But, then again, I have small fishies.