Do not make the same mistake i did. about 8 months ago i bought a 2 inch blue cray and put it in my community tank. All was peaceful until recently, it has caught and eaten: a 3 inch highfin pleco, all of my ramshorn snails, am left with 5 neons out of a school of 20 and two platties from a school of 7. this in a 200lt tank (not sure what that would be in Gallons). Ghost shrimp are fine as juveniles but get mowed at adult size. When the lights go out the feast begins, they even learn the best way to hunt your fish.
He lives by himself now, the survivors transferred into a planted 60lt tank. i stock his tank with tadpoles from the local pond for something to look at but have never seen one make it to adult. These guys eat anything and everything, and will rearrange your tank to their liking.
But... they are amazing creatures to behold, just stock your tank with cheap fish that you won't get attached to, (not that you will get the time) and all should be good