Food availability for exotic pets

Have you experienced shortage of food for your exotic pets?

When I was young, my aunt had an aquarium. During that time, there were no pet shops and the food of the fish was the mosquito eggs called dapnia. Kids hunt them in the canal and sell them to aquarium owners like my aunt. But when there was an epidemic of cholera, the children were disallowed to play in the canal. No more food for the fish... they died.

Another case is a neighbor's love birds which feed only bird seeds. There was a time that bird seed was not available and our neighbor had to search high and low to be able to buy.