Cichlids + Crayfish=

Crayfish Especially when they molt their shell.

I would say at that point they are the most vulnerable. Although, I have heard of someone keeping Crayfish w/cichlids....I wouldn't recommend it. (mind you that's only
1 success story I've
EVER heard.)
Hope I wasn't unclear
In the right setup crayfish are fun to keep and watch, IMO.(I had blue crayfish)
----edit===
Just do a search on this forum or google for more info.

READ A TON

to get the most knowledge you possibly can. Keep in mind that reading other people's facts and opinions may contradict so reading a ton is a very good idea.
Don't keep crayfish w/slow moving fish or bottom feeders. Mine actually caught one of my corydora's and was eating it alive. (I made my hubby stick his finger in to scare the crawdad and let the cory go...I wasn't going to touch that cool freaky thing. The cory did live past that incident.) It might be slighty inhumane, but after the cory incident, I made my hubby break the pinchers off the crawdad and he couldn't catch my fish. He still ate with his other grabby things in front picking up the food! They grow back after each molt(shedding his shell). Only keep 1 per tank. They don't do well in groups. I had two and they fought and 1 died(darn it...i learned the hard way). Mine ate algea wafers, flake food, earthworms(my hubbies a fisherman so we always have a supply, plus my tiger barbs enjoyed the worm too) and we had put in little pieces of veggies too. Carrots and such....Again make sure to read about it! Another thing I thought of, they need a place to hide! They can get kinda big...5" or so. Maybe a little bigger!