Should I set my colony free?

[Whitelotus]

The colony started with one queen.

[JDSweetMeat]

That's very odd behavior that I haven't seen in any of my Tetramorium colonies. I would say that if it continues, you should freeze the colony and start over with a new queen since they are so easy to find. No matter what, DO NOT release an invasive ant species back into the wild.

Tetramorium are naturalized into most areas of the world in which they have invaded. That is to say, they do not pose a big threat to local flora or fauna, and have "found their balance," so to speak.

If they do not harm humans or the native ecosystem, then there is absolutely nothing unethical with releasing them. The only reason to forbid releasing invasive species is if they have potential to cause harm. Tetramorium have no potential to cause harm. It is therefore okay.

[Helianthus]

I respectfully disagree that releasing this colony has NO potential for causing harm. Tetramorium are naturalized, but they still displace nesting habitat for native ants and compete for limited resources. This colony is in decline, so releasing it would probably just mean their death anyway, and that brings up another point: releasing captive raised colonies poses the risk of spreading pathogens to wild colonies. Many people oppose releasing even native ants for this risk. It's simply not worth it. This odd behavior in the colony could be a sign of some underlying illness.
An example of the risk is illustrated by captive raised bumblebees. Bumblebees have recently been raised in greenhouses to pollinate tomatoes and other nightshade plants. It is believed that these captive colonies have helped spread various diseases when workers manage to escape. Several North American bumblebee species are currently in danger of extinction due to these new diseases among other factors.
I urge you to keep the colony as best you can or euthanize them in some humane way.

[PwnerPie]

Picture of the setup? How are you heating them? What's the ambient temperature?