Question

Which one of the following is not an oviparous fish?
A. Clarias
B. Sark
C. Gambusia
D. Rohu

Answer 1

It belongs to family Poeciliidae. They are also known as mosquito-fish. They are principally found in freshwater habitats but some species may be found in brackish water and saltwater. As they are not oviparous it means they are viviparous i.e. they give birth to the young ones and do not lay eggs.

Step by step answer:
Clarias which is a freshwater fish is oviparous animals i.e. they lay eggs. It is also known as catfish.
-Rohu the carp or Labeo occurs in rivers and streams in India and is a crap fish. It is oviparous as it lays eggs.
-Gambusia known as mosquito-fish feeds on larvae of mosquitoes i.e., a biological method for preventing malaria. It is viviparous as it gives birth to its young ones.

Hence, the correct answer is option C. Gambusia

Additional information:
Gambusia is introduced into ponds to eat mosquitoes as a consequence they are introduced widely outside their native range and frequently become invasive threatening local species. They are not usually kept in aquariums due to the relative lack of color and aggressive nature. Clarias is carnivorous. It can live out of water for many hours because it has accessory respiratory organs called arborescent or dendriform organs for air-breathing. It can walk on land on its paired fins. Labeo or rohu is carnivores when young but becomes herbivores in adulthood.

Note: Clarias, rohu & sark are all oviparous animals as they lay eggs whereas the gambusia is a viviparous animal as it gives birth to young one not lay eggs.