IAS Gyan

Daily News Analysis


19th July, 2023 Environment

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  • State of Andhra Pradesh has recently released millions of Gambusia fish in many water bodies of state in a bid to control malaria, dengue and other mosquito-borne diseases.

Other Details

  • As per Union Ministry of Health and Family Welfare, Government of India (MoHFW), in 2022, there were approximately 6,391 dengue cases and 2,022 malaria cases in the state.
  • State of Andhra Pradesh saw a significant rise in the dengue and malaria cases.
    • In last 6 months the state witnessed 2,339 dengue and 1,630 malaria cases.

Gambusia Fish

  • The fish belongs to family Poeciliidae and genus Gambusia.
  • This fish species shows a high breeding capacity for instance 900 and 1200 offspring could be produced during the lifespan of a single female Gambusia.
  • The fish is also known as mosquitofish or gambezi.
  • It is used as a biological agent for controlling mosquito larvae across the world.
  • G affinis has a sister species, Gambusia holbrooki (G holbrooki), also known as the eastern mosquito fish.


  • These fishes are small in comparison to many freshwater fishes.
  • These can grow up to 7 cm (2.8 in) in length and can survive in diverse environments.
  • They are generally larvivorous however they also eat zooplankton, small insects and detritus material.
  • A full grown fish can eat as much as 300 mosquito larvae per day.

Habitat and distribution

  • It is considered one of the most widespread freshwater fish in the world.
  • They are commonly found in shallow waters which are protected from larger fishes.
  • As per MoHFW,
    • Native region of Gambusia affinis (G affinis) - waters of the southeastern United States.
    • Native range of the mosquitofish - southern parts of Illinois and Indiana.


Concerns of Invasive species

  • A high breeding capacity, which is 900 and 1,200 offsprings per female fish, during its lifespan lead to an imbalanced high population of this species in aquatic ecosystems.
  • A season is 30 days long on an average and young ones are released in broods of 25-30 at a time.
    • It may lead to more competition between other species for resources.
    • They may prey upon native species thus harming the natural biodiversity in the state’s freshwater bodies.
    • They are known to eat the eggs of competing fishes and frog tadpoles; Chase other fishes and restore to fin-nipping.
  • Gambusia is one of the 100 worst invasive alien species in the world according to International Union for Conservation of Nature (IUCN).
  • For example in Nainital India, mosquitofish was introduced in 1990 for controlling mosquito borne diseases. It had affected the ecosystem health of the Nainital lake.

Other Concerns

  • Introduction of this fish, however a good biological control method for source reduction, can only be a part of an integrated approach that involves various other methods like chemical spraying.
  • There are no conclusive studies about the effectiveness of Gambusia as a viable mosquito control.
  • G holbrooki may be ineffective for mosquito control, as mosquito larvae comprise a negligible part of its diet.
  • Not much monitoring and regulation of operations like Gambusia breeding, distribution and introductions and
  • No data availability for taking remedial measures.

History and Background for Disease control

  • For more than 100 years Gambusia has been used to control mosquito borne diseases across the globe, including India.
  • In India, this Mosquitofish, since 1928, has been part of various malaria control strategies and previously introduced in freshwater bodies across the country, like Andhra Pradesh, Chandigarh and Uttar Pradesh.
  • However few reports suggested that Gambusia’s predatory efficacy is reduced in running water streams, water bodies with high insecticide levels and waterbodies with thick vegetation.

More corrective measures

  • Reducing and frequently cleaning the number of mosquito breeding sources like puddles and open drainages. – kerosene oil could be used to hamper/destroy lava growth.
  • Vegetation can be cleared which host mosquitoes feed.
  • As per WHO this fish species should be used in man-made breeding habitats, like swimming pools and garden ponds, and not in natural environments.
  • Biologists and fish taxonomists should be encouraged to identify river basin-based lists of native fish species that can control mosquito larvae.

Conservation Status

  • IUCN classifies this fish as ‘Least Concern’

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Consider the following statements about Gambusia Fish:

1. This fish species is found effective in controlling not only Malaria but Dengue also.

2. They are considered alien species and a threat to native ecosystems.

Which of the statements given above is/are correct?

A. 1 only

B. 2 only

C. Both 1 and 2

D. Neither 1 nor 2

Answer: (C)