Cobalt Blue Lobster Questions

Hay, I just picked up 4 cobalt blue lobsters for $5 each, got them from a guy selling them on kijiji. They are in a 40 gallon. Any info on them would be appreciated. They are babies. What is the best thing to feed them as a staple diet? Right now they are pail because they are stressed but I know each time they shed they get more and more blue but any input about them would be great. Also are they hard to breed?