Aleksei Korotnev's principal work was on the embryonic development of rats; he also made extensive zoological collections in the Indian and Pacific Ocean regions, and studied the fauna of Lake Baikal in 1900 and 1902.
His principal work was on the embryonic development of cnidarians, bryozoans, tunicates and insects. In 1885 and in 1890-91, he made extensive zoological collections in the Indian Ocean and Pacific ocean regions. Korotnev also studied the fauna of Lake Baikal between 1900 and 1902. 
