If you're worried about their getting enough food, give 'em Hikari Tropical Crab Cuisine. They're pellets that contain calcium iodate, so not only do shrimp love them - they're supposedly good for them. My C. japonica actually fight over the pellets, so I have to make sure to toss in one for each shrimp.
If you do have a tendency to over-feed, make sure to stay on top of things - don't let the water get foul because shrimp are particularly sensitive to poor conditions. In an established tank, it's always better to under-feed them than to over-feed, but sometimes those little buggers look at you with those googly little eyes and you just can't resist :wink: .