The renown of the little guppy Poecilia reticulata has grown substantially. The fish has been put into ponds and ditches in an effort to consume mosquito larvae for decades. Scientists, however, view it as an invasive species with a remarkable capacity for reproduction and dissemination.
- Now that health officials in places with mosquito-borne diseases such as Zika are considering extending the use of these predatory fish, ecologists urge them to reconsider.
- In a report published online today in Biology Letters, a group of ecologists contends that guppies and other non-native fish employed for mosquito control have not shown to be very efficient mosquito fighters and pose ecological concerns.
Rana El-Sabaawi, an ecologist from the University of Victoria in Canada and lead author of the new article, says, “It all seems like magic: you throw the guppies in, they eat the mosquitoes, and everything is wonderful.” “Our fear is that you are recklessly introducing a potentially invasive species.” At the start of the twentieth century, larva-eating guppies may have been cutting-edge technology for British colonialists attempting to rid their dominion of mosquitoes.
El-Sabaawi was startled to learn, however, that large-scale initiatives are already ongoing, as she finds the concept so dated. She discovered, while “randomly Googling guppies,” that Pakistani health officials had released thousands of the fish into the ponds and sewers of Karachi in 2013 to combat the spread of dengue virus.
El-Sabaawi was upset by footage of a local government employee allegedly “wandering with a lot of guppies and essentially just putting them in ditches” in a widely disseminated news film chronicling Zika control efforts in Brazil. El-Sabaawi and her co-authors find this unsettling since guppies are effective intruders.
They are robust and productive, able to survive in somewhat filthy water, reproduce frequently, and give birth to live, rapidly developing young. A 2011 assessment found that the species had expanded from its original habitat in the Caribbean and the northern coast of South America to at least 69 nations due to unintentional aquarium releases and mosquito control initiatives.
Moreover, several research indicate that introduced guppies pose a harm to biodiversity. Researchers in Hawaii discovered that the introduction of guppies in the 1920s reduced native fish populations, possibly due to competition for food and housing space, and altered the water’s nutritional cycle: Due to the presence of ammonium in fish urine and gill secretions, algal growth was enhanced in guppy-rich locations with elevated levels of dissolved nitrogen.
- Another frequent mosquito-control fish, Gambusia affinis, has also been linked to decreases in native fish species.) Additionally, the authors wonder whether guppies are reliable mosquito predators.
- According to them, studies supporting their efficacy typically have problems.
- In laboratory experiments, fish were frequently starved before being fed just mosquito larvae.
And field research has been limited and poorly designed. John Hustedt, senior technical officer of the non-profit Malaria Consortium in Phnom Penh, says that dismissing guppies as a control strategy is counterproductive. The Malaria Consortium has been releasing the fish into water storage jars in rural households to combat dengue fever and other mosquito-transmitted diseases.
- Hustedt thinks that a recent study conducted by his team would give further proof of the benefits of guppies.
- In houses with guppies, the number of adult mosquitoes decreased twice as much as in those without guppies, according to preliminary findings.
- If someone comes out and says, ‘Actually, it doesn’t work and it will cause you problems,’ it might lower the likelihood that the government would be more willing to attempt it on a wide scale,” he explains.
Concerning ecological dangers, guppies contained in separate containers may be less likely to spread than those discarded in urban sewers and ditches. Nonetheless, Hustedt doubts the difference between native and non-native for a species that is already so widespread.
The origin of the guppies utilized in his study is unknown; they were discovered on a farm in a region outside of Phnom Penh. “It appears to me that they’ve been here for quite some time, and they’re already established in the ecosystem,” he adds. Despite the fact that the advantages and harms of guppy release may be very context-dependent, some researchers take a harsh position.
“Authorities should discontinue the use of fish to manage mosquito disease vectors,” argues Valter Azevedo-Santos, an ichthyologist at So Paulo State University in Botucatu, Brazil, and co-author of a letter published in Science this year protesting to the technique.
- He argues that money would be better spent on pesticides, hygienic measures such as removing standing water from dwellings, and even the experimental release of genetically modified mosquitoes to carry a fatal gene.
- He believes that this report would give health professionals pause as they search for methods to battle Zika.
He states, “This mismanagement must cease immediately, otherwise further fish invasions will occur in the near future.” This is a unique occasion.
Which fish consumes mosquitoes?
Mosquitofish are so proficient at eating mosquitoes that its name is derived from this trait. A mosquito fish may devour up to 160 wrigglers each hour. These fish are indigenous to the eastern United States south to Alabama and west to Texas. The female develops to roughly 2 3/8 inches in comparison to the male’s 1 5/5 inches.
The non-pregnant females are dull gray, fairly thin, and have spherical, translucent fins, but the males are more robust. He has clear gray sides with blue iridescence, an olive-brown back, a silver belly, and a black bar running across each eye. The male utilizes the gonopodium, an extended portion of the tail fin, to fertilize the female.
The mosquitofish is indifferent to the pH, acidity, or alkalinity of the water, as well as the hardness or softness of the water. Hard water contains several minerals, including calcium and magnesium, but soft water does not. One of the reasons mosquito fish are so effective at collecting wrigglers is that they flourish in the quiet water where wrigglers are prevalent.
Which fish can I add to my pond to prevent mosquitoes?
Conclusion – Which Fish Should I Use To Control Larvae? – Goldfish and koi are wonderful options for bigger ponds, but they may also be employed to manage the population of smaller fish. Public domain. This actually relies on your particular preferences and the characteristics of your pond.
As noted in earlier articles, each fish have distinct pH and temperature requirements, as well as variable pond depth and size requirements. Always conduct study prior to deciding which species to fill your pond with. Generally speaking, it is ideal to keep fish species of comparable sizes together to reduce predation.
A mix of koi, sizable goldfish species, and golden orfe would work well in a large pond since they are of comparable size, have similar pond requirements, and normally get along nicely. Koi do not consume a substantial amount of mosquito larvae, thus pairing them with these other fish species can help you maintain pest management.
You might also place a plecostomus at the bottom of your aquarium to consume any leftover algae or bug larvae from your other fish. Use these species only if your pond is at least one meter deep and at least 1,000 gallons per every four fish. These bigger species are also better equipped to survive seasonal temperature swings and do not reproduce as rapidly as the majority of smaller fish species.
However, smaller fish are considerably more likely to consume mosquito larvae as a natural component of their diet. Consequently, if you have a certain mosquito population, a smaller pond (or a lesser budget), a combination of goldfish, mosquito fish, minnows, and guppies will eliminate all mosquito larvae.
- Eep in mind, however, that mosquito fish and minnows can endure a broad temperature range (34-104°F and 41-72°F, respectively), but guppies are more sensitive and require water temperatures between 70 and 80°F.
- In many regions, mosquito fish are regarded as an invasive species, so you must ensure, first, that they are legal in your area and, second, that your pond is not close to a natural canal from which they may escape.
Truly, mosquito fish are only suggested if you have a serious mosquito issue. All varieties of goldfish devour larvae voraciously, and because to the wide variety of goldfish available, you may easily choose a species (or many species) that will work well with your budget, climate, degree of experience, other fish species in your pond, and pond size. 
What may consume mosquito larvae? – Fish include goldfish, guppies, bass, bluegill, and catfish. The larvae of mosquitoes and other water insects. The larvae feed on a blood protein called hemagglutinin (HA) found in the blood. Blood that is red, yellow, orange, brown, or black is attractive to mosquitoes.