Camponotus fragilis are very active ants, especially at night. When they are hungry, they will be constantly at the cotton, which means having an outworld or a tub and tube colony setup helps a lot with caring for them. Otherwise, keeps may experience problems such as having to deal with escapees all the time.

The ants will need both a source of protein and sugar right when they get workers. From my experience, these ants do not have very large nanitic batches, but after the first workers eclose, they start producing a lot of brood. Some sources of sugar for C. fragilis include honey, sugar water, byFormica sunburst and perky pet hummingbird nectar. You can feed them protein by giving them small insects like fruit flies, or cut up roaches and mealworms. They also enjoy eating soft-bodied spiders. Other sources of protein that have worked well for me in the past include rehydrated Hikari Freeze-Dried Bloodworms. Occasionally, the ants will also take some chicken or other human meat if no insects are available.

It's very important to cycle through different foods for the ants, as one type of food is not enough for them to obtain all the nutrients they need. For example, I would switch around the type of protein I feed them every other time, feeding fruit flies one day, and bloodworms the next. I would make sure that the ants have constant access to sugar when they need it and feed protein every other day. While the small colonies may not eat much, it is still important for them to have access to a steady source to keep up brood production.

Any setup would work for C. fragilis as long as they have both a nesting area and a foraging area. Unlike some other ants, they are not very picky about where to live. Early deaths in colonies of C. fragilis are not uncommon, but should still be noted with care. Causes of deaths may include poisoning, and it is important to trace any symptoms back to its source.

Fluon has worked as a containment barrier for me in the past. Other barriers, such as pipe sealant have also worked. However, the ants are also very persistent in climbing, and they may simply leap over the barrier or find a workaround, so barriers should be observed and fixed if needed every month.

I've had the most success with feeding sugar through liquid feeders because the ants have a tendency to bury sugar water if they are unable to drink all of it. This means that if there are open sources of liquid, they may pull apart the cotton in their tube to cover it up, which could lead to the cotton collapsing and drowning the ants.

Substrate is not necessary for keeping C. fragilis since their brood can form pupae without it. However, it is still helpful, just in case the water in their tubes leak and threaten the brood. I would make sure to heat the colonies with care, as the ants will try to move their brood away from sources of heat if it is too hot. If they move their brood onto the cotton in the tube, it may damage the pupae, which have to stay dry.