Learn Turkish: Tespit ettik ki soğuk suda üremiyorlar. - We determined that they do not reproduce in cold water.

Traditionally, Turkish embeds this kind of fact using the object participle: Soğuk suda üremediklerini tespit ettik. However, using ki allows an English-like structure (Main Clause + ki + Subordinate Clause). This structure is very common, especially with complex statements, long explanations, or when the speaker wants to emphasize the main verb first.

How exactly is the word üremiyorlar formed from the verb üremek?

The root is üre- (to reproduce/breed). When we add the negative suffix -me followed by the present continuous suffix -yor, a rule called "vowel narrowing" happens. The wide vowel e in the negative suffix narrows to i because of the y that follows it. So, instead of üremeyorlar, it becomes üremiyorlar.

Is the word order fixed when we use ki in this way?

Yes, the order is quite strict compared to normal Turkish sentences. When you use ki as a complementizer (meaning "that"), the main verb (tespit ettik) almost always comes right before it, and the full factual statement (soğuk suda üremiyorlar) comes immediately after it. You generally cannot scramble these two halves.

Can I use ki with any verb to mean "that"?