What effect did the introduction of the Nile perch have on Lake Victo…

The correct answer is Option (1) → It caused the extinction of more than 200 species of cichlid fish

An alien species is one brought into an area from outside. Some alien species turn invasive: they spread fast and cause the decline or extinction of the native species. The Nile perch, a large predatory fish, was brought into Lake Victoria in East Africa. It fed on the native fishes and led to the extinction of a unique group of more than 200 species of cichlid fish.

Option (1) It caused the extinction of more than 200 species of cichlid fish — Correct. The Nile perch preyed on the cichlids and wiped out more than 200 species of them.

Option (2) It had no significant impact — Incorrect. The impact was huge: a whole assemblage of species was lost.

Option (3) It improved water quality — Incorrect. The book records the loss of species, not any gain in water quality.

Option (4) It increased the population of cichlid fish — Incorrect. The cichlids did not increase. They were driven to extinction.

NCERT Extract:
Loss of Biodiversity – “… (iii) Alien species invasions: When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction of indigenous species. The Nile perch introduced into Lake Victoria in east Africa led eventually to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake.”