Alien species invasion leads to extinction of indigenous species' - Justify this statement by considering two animals as examples.

Explanation

(a) Introduction of Nile Perch into Lake Victoria in East Africa led eventually to the extinction of more than 200 species of orchid fishes in the lake.
(b) Introduction of African catfish Clarias gariepinus for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers.