The Health Department is also planning to release Gambusia fish in mosquito breeding water sources to feed on mosquito larvae across the district.
A concrete water tank on the DHH campus, which was used for fish farming has been recently renovated at a cost of $469 (Rs 30,000). District Malaria Officer said the tank of 20 feet long, 10 feet wide and 10 feet deep will work as a mother hatchery in the district.
Gambusia and Guppy varieties of fish will be bred here and distributed to small hatcheries in sub-divisional hospitals and community health centres, the offer adds.
Around 1,500 fish fry of Gambusia and Guppy have been released into the tank, the officer said and added that both the species feed on the larvae of mosquitoes. While a Gambusia fish eats 100 to 300 larvae a day, a Guppy fish eats 80 to 100 larvae.
It is like nipping malaria in the bud before the larvae gets converted into pupa and adult mosquito, Das said.
Gambusia fish will be released in water bodies and stagnant water sources in the rural areas, while the Guppy fish will be released into drains in urban areas.
It has been found to be easy to maintain the centralised stock of both the fish species at negligible cost, the officer said.
The officer also said that Gambusia and Guppy fish survive in all types of water and after maturity breed throughout the year at about four weeks interval.
The important aspect is that it does not require specialised equipment for transportation, he added, and hoped that the intervention would work without affecting the environment.
According to sources, 9,209 patients tested positive for malaria in the district in 2012, while the number was 9,556 in 2013 besides two deaths.
Similarly, 18,812 patients were found positive for malaria in 2014 of which one patient died while the number was 2,697 patients till March 31, 2015 this year.
For the first time the fish, which have been used in India since 1928, will be distributed to all 47 PHC's in the district to prevent the outbreak of the disease caused by mosquitoes. Fish have been taken up in order to curtail the disease, especially dengue.
Gambusia fish can adapt to wide variations in temperature as well as to chemical and organic content of the water but does not tolerate very high organic pollution.
The optimum temperature for reproduction ranges from 240C to 340C but the fish can survive at freezing temperatures.
The fish frequent areas especially suitable for the mosquito larvae. It lives and multiplies in ponds stocked with larger fish provided the pond is shallow and has protective vegetation for refuge.
A single full grown fish eats about 100 to 300 mosquito larvae per day, he added.
An adult Gambusia (affinis affinis) measures only 2 1/2 inches in length. It can withstand a temperature ranging above freezing point to 90° F and can survive in all types of water. The species can successfully survive in overcrowding conditions. It starts breeding when it is 2 inches in size. A single fish can consume mosquito larvae equal to its own weight each day and hence known as “mosquito fish”.
An adult female Gambusia (affinis holbrooki) measures about 3 inches in length, while males are smaller. It can stand a temperature tolerance from above freezing point to 88°F.
During extreme cold conditions it hibernates in mud.
The species have proved to be an effective mosquito destroyer in India and other parts of the world like Burma, Thailand, Formosa, Philippines, Japan and Hawaii.
On 24 February 2014, Chennai Corporation introduced western mosquito fish in 660 ponds to control the mosquito population in freshwater bodies. Apart from Gambusia fish, Larvicidal fish are also used in relation to public health. Larvicidal fishes are an important tool for biological control of mosquito population.
Mosquitoes act as vector, transmitting several diseases to human beings from the reservoir organisms. Important and serious diseases like malaria, filaria, dengue, yellow fever, Japanese B-encephalitis and others are being transmitted through mosquitoes. Larvicidal fish by consuming mosquito larva help in reducing the population of vectors thereby minimize the occurrence of mosquito borne diseases.
The guinea worm can also be checked by the introduction of cyclopsivorous fishes like Ambasis, in order to cut down the population of cyclops, which is as intermediate host for the worm.
The gastropods and lamellibranchs, which serve as carrier for parasites, especially for animals of human food value, can also be directly checked as larvicidal fishes may feed on their larval and young forms.
Use of fish in mosquito control has been well-known for more than 100 years. In India, as far back in 1904 larvivorous fishes were used in Mumbai City for the control of malaria vector.
