Mould is not necessarily a problem, it’s usually only an issue if the ants are clearly avoiding it and moving to the other side of the test tube. If they are staying near the cotton and don’t seem to care, I wouldn’t worry too much.

Typically you should only move the ants when they no long fit in the test tube and are often escaping when you try to feed them. Moving them in too early can cause them to become stressed and develop slowly.

You will need to feed the colony regularly by placing a small amount of food in the test tube or outworld. They will need sugars (honey, sugar water, ant nectar) and protein (mealworms, crickets, or other insects) about once every 5-7 days.

All of our queens come in a test tube, with half of the tube filled with water and blocked off by cotton. Some water seeps through the cotton and allows the queen and her colony to drink.