I turn my powerheads off for an hour at feedingtime. I know some people feel it's not good for the bacteria to be left without flowing water, but it has worked in my tanks. However, I wouldn't disregard the warning concerning turning the pumps off, I'm quite sure the bacteria colony could go bad pretty fast given the wrong circumstances. Maybe it depends on what kind of filtration system you have?
Anybody care to elaborate a bit on this?
My setup is an Eheim 2224 external pump, with an estra Rena 600 l/h internal. I turn the Rena off for an hour, but leave the Eheim on. This allows the food to lay still on the bottom, but will swirl around if suspended in the water.
Chopping the recipe small makes for alsmost no boyancy left in it, so it stays on the bottom much easier in small pieces than in large.
When all that's said Mindy, I'm pretty sure your Zebras are getting enough food, they're not totally helpless, and will eat if they find suitable food - which they will as long as not all is gone

(this goes for adults then, just to have said that too

)