How do you know when your otos are getting enough food from the algae in your tank? I am bringing this up because of a post in another forum about giving them slices of cucumber and zuchini. If I feed them veggies, will they neglect their algae scraping duties?

I've never tried to target feed my ottos other than giving them algae waffers once in awhile. The only other thing I've ever done for them, is to make sure there is at least one piece of driftwood in the tank. Not that they eat the wood like many plecos do, but they do like the bio-film that develops on the wood.
One way you can be sure they are getting enough to eat is to check their bellies when they are sitting on the glass walls. If the belly area is nice and full, you know the fish is doing well. Sunken in should give you a clue to add some algae waffers or other foods.

Thanks a lot! It is the first time I have otos and was worried they did not have enough algae. How many otos do you need to keep your plants clean?

I only have one otto right now, and he (or she) is in the 5g which is spotless.
If it was me, I would just wait a bit and see how the tank looks in a couple of weeks or so. If you see algae starting to form, you can always add more then. This depends of course on how big the tank is and how many fish are already in there.