do
NOT use those "vacation feeders"!!!!
they suck, will only make your tank a dirty mess, the fish wont eat it, and leaving all that junk in your tank for a week will only dirty the water to the point that your fish could die..
The only thing those vacation feeders are any good for is relieving you of some of your money..(actually, thats also the only reason they even exist in the first place)
fish can go a week without food with no problem at all..
I have left my discus without food for 2 weeks..just had someone come in to water the house plants and make sure the aquarium filters were running..but I didnt ask them to feed my fish!
the best thing you can is make sure the tank is really clean, do a good water change, feed *lightly* before you leave, then just go away and dont worry..
having a clean tank with no food (and also fish producing very little waste because its not eating) is MUCH MUCH better than having a big chalky block of whatever those awfull feeders are, fouling the water..
clean tank and no food is the way to go.
How big is the tank?
is it at least a 10 gallon with a real filter and a heater?
if its just a tiny bowl..then well...you have other problems..
http://www.thekrib.com/Food/vacation.html
http://www.solodvds.com/fish_tank/vacations.asp
http://groups.google.com/groups
http://groups.google.com/groups?hl=