Q.Write True or False: Clarias gariepinus reared for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers.

The African catfish, Clarias gariepinus, introduced for aquaculture, is an invasive alien species that threatens native Indian fish.

Clarias gariepinus (African magur/catfish) was introduced into India for aquaculture because of its fast growth and hardiness. However, it turned out to be a highly predatory and invasive alien species — it preys on and outcompetes native fish species (like the indigenous Clarias batrachus), disrupting local aquatic ecosystems. Because of this threat to nati …

Alien species introduced from elsewhere often lack natural predators/competitors in the new habitat, allowing them to outcompete and displace native species, causing biodiversity loss rather than gain.

Alien species invasions are recognised as one of the major causes of the ongoing loss of biodiversity globally. When a non-native species is introduced (deliberately or accidentally) into a new region, it may multiply rapidly (because natural checks like predators, parasites and competitors from its native range are absent) and outcompete indigenous species for resources such as light, nutrients and space, sometimes driving native species to lo …

The 'Terror of Bengal' is water hyacinth (Eichhornia crassipes).

Water hyacinth (Eichhornia crassipes) is an alien (introduced) aquatic weed that grows abundantly in waterbodies, choking them, depleting oxygen and killing aquatic life. Because of the devastation it caused to waterbodies, it earned the name 'Terror of …

The introduced Nile perch — an alien predator — drove more than 200 native cichlid fish species of Lake Victoria to extinction.

When the predatory Nile perch was introduced into Lake Victoria in East Africa, it preyed heavily on the native cichlid fishes. This alien (exotic) species invasion led to the extinction of more than 200 species of these ecologically unique cichl …

The statement is True — Clarias gariepinus, introduced for aquaculture in India, has become a serious threat to native/indigenous catfish species.

The African catfish, Clarias gariepinus, was introduced into India for commercial aquaculture purposes because of its fast growth rate and adaptability. However, being a voracious, highly adaptable predator, it escaped into natural water bodies (rivers and ponds).

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The Nile perch, an alien predatory fish introduced into Lake Victoria, wiped out the native cichlid fish population — a classic case of extinction caused by alien species invasion.

The introduction of the predatory Nile perch (an alien/exotic species) into Lake Victoria in East Africa is a well-known ecological example of how alien species invasions can drive native species to extinction — it eventually led to the extinction of the lake's more than 200 endemic species of cichlid fish. This is distinct from habitat loss/fragmentation (destruction of natural habitat), over-exploitation (excessive harvesting, e.g., of Steller's sea cow or the …

Water hyacinth is the classic invasive alien species famously called the "terror of Bengal" for choking Indian water bodies.

Water hyacinth (Eichhornia crassipes), a free-floating aquatic plant native to South America, was introduced into India as an ornamental plant but escaped and became one of the world's most notorious invasive alien species. It reproduces and spreads extremely rapidly (both vegetatively via stolons and via seeds), forming dense floating mats that cover the entire surface of ponds, lakes, canals and other water bodies. This unchecked growth blocks sunlight from reaching submerged plants, depletes dissolved oxygen (harming fish and other aquatic life), obstructs waterways/irrigation and navigation, and displaces native aquatic biodiversity — its extensive damage in West Bengal's …