Dengue outbreak in Firozabad: How Gambusia fish is now Uttar Pradesh's best bet to control vector-borne menace

Battling a deadly outbreak of dengue and viral fever that has claimed 51 lives so far, the Firozabad district administration is releasing about 25,000 mosquitofish that eat larvae of dengue-breeding mosquitoes in ponds to check the spread of the disease. District health officials have started releasing the fish, generically known as Gambusia, in ponds in urban as well as rural areas of the district, Chief Medical Officer (CMO) Dinesh Kumar Premi told PTI. He said 50 packets of fish seeds have been acquired from Badaun to start with. Premi said the district administration is going with the experiment having seen its success earlier in Bareilly and Baduan districts. The CMO said that a Gambusia fish eats about 100 larvae daily. The measure will also be effective against malaria, he added. Dengue and viral fever have claimed 51 lives in over a fortnight in the district in Uttar Pradesh. Hundreds of people are also undergoing treatment for the diseases. District Magistrate Chandra Vijay Singh had recently directed health and municipal corporation officials to conduct a door-to-door survey to drain out stagnant water from coolers, pots and other utensils. What are Gambusia fish? Fish have been widely used in public health, since as early as 1903. One of the most successful and widely used biological control agents against mosquito larvae is the topwater minnow or mosquitofish Gambusia affinis. Fish other than Gambusia which has received the most attention as a mosquito control agent is Poecilia reticulata, the common guppy. Many health departments also use guppy fish to check the spread of mosquito-borne diseases. They are bred in the same manner as mosquitofish. “Guppy drives” have been carried out in Tamil Nadu, West Bengal and Gujarat, while Gambusia have been used by civic administrations in Punjab’s Mohali and Amritsar and Haryana’s Panchkula, along with capital Chandigarh, reports News18. Bred in ponds, wells and smaller water bodies, these fish are known to check the spread of mosquito-borne diseases like malaria and dengue. As per  The Tribune, Dr Kanwarjit Singh, joint director of animal husbandry and fisheries, Chandigarh UT, said adult Gambusia could eat up to 150 mosquito larvae in an eight-hour period. This makes them an excellent biological tool for mosquito control because they eat the larvae before they have a chance to develop into adult mosquitoes, he added. However, the use of Gambusia and guppy fish as biological weapons to control mosquito menace have had also been reported to have the opposite effect as well. Four hatcheries of the Cuttack municipal corporation in Odisha have turned into a breeding ground for mosquitoes, according to The New Indian Express. The reason is this was the fact that all the hatcheries have been lying defunct over the past several years due to lack of maintenance, turning into breeding grounds for mosquitoes due to stagnation of rainwater. What are the advantages of this type of fish?

• These fishes are self-perpetuating after their establishment and continue to reduce mosquito larvae for a long time.
• The cost of introducing larvivorous fish is relatively lower than that of chemical control.
• The use of fish is an environmentally friendly method of control.
• Larvivorous fish such as Gambusia and Poecilia prefer shallow water where mosquito larvae also breed.

What is the breeding season of fish? Gambusia breeds throughout the year after maturity, especially in tropical conditions. In relatively colder climates such as is found in the north and north-west India breeding period lasts from May to September and in the warmer climate of southern India from April to November. With inputs from agencies