The latest issue of Kodansha's Afternoon magazine announced that the manga will end on September 25th.
The creator of the work, Nihei Tsutomu, launched the manga in 2009, and Kodansha published the 14th volume in February. Nihei had already hinted that the manga was reaching its climax.
Shidonia no Kishi had two seasons; the first premiered between April and June 2014, and the second season arrived in April of this year, titled Knights of Sidonia: Battle for Planet Nine, being shown dubbed in Portuguese on Netflix, shortly after the end of its broadcast in Japan.