Kedril Trir

Kedril Trir starts to develop if a Tleis is alone and far from their hive for too long. Or collectively in a very small group, though the process is much slower, and much worse to experience.
The most likely victims of Kedril Trir are Tleis who are survivors of a pack that'd been attacked by predators and had less than a dozen stragglers left.

Stages of it are a bit blurry, and depend on the specific case. A solo individual might just start just thinking to themselves, repeating stories they've heard to try keeping themselves company. This gradually progresses into delusions, occasionally they might start hallucinating things, which only get worse as it progresses further.

When it progresses from Vaz Ikzel the individual starts off reveling in the silence in their mind. Rather than trying to stop the silence by talking to themselves. After a day or two it starts to progress basically as normal, except they aren't trying to get back to their hive as it happens.

Very early stages and being around larger groups of Tleis. Which sounds simple but when you live in the ocean finding even large groups of your own kind can be really hard. Any Tleis found in mid-later stages are killed out of mercy.

Progression from Vaz Ikzel is an exception: normal treatment will only make it worse.

For a lone individual early stages occur within days. If they are lucky enough to regroup before it progresses they're likely to at least mostly recover.
Mid stages occur anywhere from 3-6 days, usually 3-4, and cause permanent, irreparable mental damage. They'll never completely recover, and chances are very high they'll still get worse. Causing this stage to basically be known as a point of no return.
Late stages usually occur at 5-7 days, and lead the individual to their death not long later. Assuming they haven't starved to death before then

Average expected lifespan after separation is 1 Sikses week (8 of their days) for a lone Tleis. But there is a case of a Tleis that managed to survive for 2 Sikses weeks alone. Before being found by a hive and killed out of mercy as they were too far gone to be saved.