In Ahmedabad district, an innovative approach is being taken to control mosquito-borne diseases. Diseases like malaria, dengue, chikungunya, and Zika virus pose a significant challenge globally. To tackle this, biological control methods are now preferred over traditional chemical methods. These methods are safer and environmentally friendly. For the past five years, Ahmedabad has focused on using biological control methods. Gambusia affinis and guppy fish are being widely utilized to reduce mosquito populations. These small fish, measuring 4 to 6 cm, do not eat mosquito eggs but consume their larvae, effectively reducing their numbers. A single adult fish can eat between 100 to 300 larvae daily.
The reproductive capacity of these fish is remarkable. One fish can give birth to 200 to 300 offspring four times a year, resulting in 800 to 1200 new larvae eaters annually. Under the guidance of Ahmedabad District Collector Sujit Kumar, District Development Officer Videh Khare, and Chief District Health Officer Dr. Shailesh Parmar, various hatcheries have been developed across Ahmedabad. These include natural ponds, constructed hatcheries at primary health centres, and public-private partnerships. In total, there are 264 hatcheries in Ahmedabad, comprising 97 natural hatcheries and 167 constructed ones. As of now, fish have been released in 745 locations, showcasing the commitment to biological mosquito control.
The two main types of predatory fish in use are Gambusia affinis and Poecilia reticulata (guppy). These fish are small, slender, and greyish-black in colour, measuring 4 to 6 cm in length. They can be released in permanent water bodies such as ponds, tanks, and slow-flowing canals. Typically, 5 to 10 male and female fish are placed in one square meter of water. Their breeding season lasts from April to November, ensuring a continuous increase in their population. A natural predator, these fish are efficient in controlling mosquito larvae. It’s important to note that they only consume larvae and do not feed on adult mosquitoes or their eggs. Humans do not use these fish as food.
By adopting this biological method, we can significantly reduce the burden of mosquito-borne diseases and create a healthier community. As of July 23, 2025, there have been no reported cases of malaria in Ahmedabad, according to District Malaria Officer Narendra Singh Rathod.
### What is Biological Control?
Biological control refers to the use of living organisms to control pests. In this case, predatory fish are used to eat mosquito larvae. Unlike chemical methods, this approach does not harm the environment. Interestingly, predatory fish have been widely used in public health since 1903. There is a push to increase the use of these fish in rural areas as a biological control method.
### Where Chemicals Are Not Possible, Predatory Fish Work
In large ponds or reservoirs where animals drink water, owners often avoid using chemical treatments, which allows mosquitoes to breed continuously. However, if predatory fish are introduced, mosquito breeding can be stopped. When animals drink water, the fish stay submerged, avoiding any harm. Additionally, these fish can be placed in areas that hold water for 4 to 6 months during the rainy season. This method also prevents the breeding of nuisance mosquitoes that transmit malaria, dengue, and chikungunya.
The Gujarat government’s relentless efforts for malaria elimination have resulted in a significant drop in the positive malaria rate to below 1 per 1,000 residents. Consequently, Gujarat has been upgraded from category 2 to category 1 in the nationwide malaria elimination program. In 2024, over 1.81 crore patients received free diagnosis and treatment for fevers. All health centres in the state continue to offer free malaria diagnosis and treatment. This year, approximately 2.0 lakh residents in 196 villages will receive insecticide spraying.
Under biological control efforts, a total of 3,863 predatory fish breeding centres are operational. Under the guidance of Chief Minister Bhupendra Patel and Health Minister Rishikesh Patel, free malaria diagnosis and treatment are provided across the state. The health department conducts intensive surveillance and demonstration of predatory fish, fever surveillance, and blood screening of workers at construction sites. During 2024, an estimated 2.52 lakh residents in 233 villages were covered under insecticide spraying.
Public awareness programs are organized by the state government on World Malaria Day to promote malaria awareness. Various programs such as dramas and puppet shows are conducted in public places. Events in schools and colleges raise awareness about vector-borne diseases. World Health Organisation (WHO) promotes World Malaria Day on April 25 to enhance public participation in malaria control. This year, the theme is “Malaria Ends With Us: Reinvest, Reimagine, Reignite.”