The amount crocodilians eat and how often varies with size and age. Hatchlings are hungry little critters and will hunt insects and small fish every day. As they grow older, the time between meals can grow substantially in some cases. Yearlings will eat every couple of days, but have no problem gorging themselves on a school of fish and then not eating for a week. If an adult has hunted and eaten particularly large prey, they may not need to eat for a month or sometimes even longer.
Because of their slow metabolism, adult crocodilians can go for extremely long periods without eating surviving off of fat stores in the body. Certain species routinely go for long periods throughout the course of their lives without a meal during times of drought or cold temperatures. Stress can be another factor causing crocodilians to not eat, and large crocs who are overly stressed from being placed in captivity have been observed to survive nearly 2 years without eating!!