Weird Feeding question....

Eww ... don't stick lettuce or any other food in your tank and then leave. You'll regret it.

Honestly, unless you have someone trustworthy who won't over feed your fish, you're better off just letting them go for the two weeks. If those fish are overfed, it will polute the water and that's a way bigger problem than two week fast. Unless you have very young fish, they should all be ok. I'd make sure to do a good water change before I left and then leave it at that.

think very cloudy water, possibly a clogged filter, and maybe even some fungus. yummy.

If your really worried about not feeding for a week (you shouldn't be) then you can fatten up the fish for a week before you leave. Feed high fat frozen foods like blood worms. Feed more often than usuall, and do a big water change before you leave. the fat reserves will hold your fish longer than a day or two of lettuce will. A big clump of java moss dropped into the tank will also provide some micororgansims for them to pick at without fouling the water.

The other hazard of leaving any organic in the tank is an ammonia spike--not good for the fish. If you can, find someone who could stop in every third or fourth day, and have packages of the food for them to add to the tank. It works well--the person just adds the amount of food you indicate, and can check to make sure the tank is still running--ie, filter, lights, heaters all doing their job. I've had three different people watch my tanks with no problems. Just show them what to do, and leave the same info in writing.

But--I would have no qualms leaving my FW setups unattended for 2 weeks. The fish will be fine--especially in planted tanks.