Fun Eastern Mosquitofish Facts For Kids | Kidadl


Fun Eastern Mosquitofish Facts For Kids

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Have you ever heard of a problem solver becoming the problem? We will introduce you to one such fish species which was introduced to control pests, but in turn, it became a pest creating havoc for humans.

The species we are talking about here is Gambusia holbrooki (Eastern mosquitofish) which was introduced to the aquatic habitats of Australia in the 1920s to control the mosquito population as these fish mainly feed on mosquito larvae. But it was soon discovered that the mosquito population increased instead of decreasing. Surprising!

It was found out that this aggressive voracious eater was killing the native fish species of Australia, which were better at controlling the mosquito population. In addition, this Eastern mosquitofish species also ate frog eggs and tadpoles, affecting the population of frogs which are also the predators of mosquitoes and their larvae. The Australian government took many measures to control the spread of this invasive species, but it has been facing many challenges because of the species' highly adaptive nature.

Read on to know some more interesting facts about this mosquitofish species. If reading about fishes interests you, check out the x-ray tetra and African lungfish.

Fun Eastern Mosquitofish Facts For Kids

What do they prey on?

Mosquito larvae, zooplankton, small insects, detritus material, frog eggs, tadpoles

What do they eat?


Average litter size?


How much do they weigh?


How long are they?

Male: 1.3 in (3.5 cm)Female: 2.3 in (6 cm)‍

How tall are they?


What do they look like?

Brown or green on top and silver on the bottom

Skin Type

Wet, slimy scales

What were their main threats?

Humans, Birds

What is their conservation status?

Least Concern

Where you'll find them?

Ponds, Lakes, Coastal Waters, Freshwater Rivers, Brackish


Eastern United States









Eastern Mosquitofish Interesting Facts

What type of animal is an eastern mosquitofish?

The eastern mosquitofish or Eastern gambusia is the native fish species of southern and eastern United States from Pennsylvania to Florida and Tennesse to Alabama.

What class of animal does an eastern mosquitofish belong to?

This native fish of the United States belong to the class of Actinopterygii.

How many eastern mosquitofish are there in the world?

The exact number of eastern mosquitofish across the world is not available. But these native fishes of the United States consist of about 40 species that include both freshwater species and species that live in saltwater or brackish habitats. These fishes are highly invasive species, especially the G. holbrooki and Western mosquitofish or Gambusia affinis.

Where does an eastern mosquitofish live?

The Eastern gambusia has a native range spreading from the eastern to the southern United States. Their native range spreads across Florida, Pennsylvania, Alabama, and Tennessee in the United States. These freshwater fishes were introduced throughout the world, especially in countries like Australia and Europe, to control the mosquito populations. But this species proved to be highly invasive, leading to the destruction of native species in those areas.

What is an eastern mosquitofish's habitat?

Eastern gambusia species are freshwater fishes and mainly habitat in ponds, lakes, slow-moving rivers, and sloughs. They prefer shallow water habitat, and their growth is optimal in a temperature range of 88°F-95°F (31°C-35°C). They can adapt well to thermal and chemical changes in the aquatic habitat.

Who do eastern mosquitofish live with?

Mosquitofish (G. holbrooki) can live with various other ornamental pond fish species of the same size. They do well with their species but are aggressive towards guppies and other fish species with fancy long fins because of their fin nipping habit.

How long does an eastern mosquitofish live?

The lifespan of the mosquitofish ranges from one year to a maximum of 1.5 years in the wild. But some have reported that this fish can live up to three years in captivity with proper care and diet.

How do they reproduce?

The breeding season for G. holbrooki (Eastern mosquitofish) peaks around summer. After mating with the male eastern mosquitofish, the females can have 50-300 eggs at a time. These eggs develop inside the body of female Eastern gambusia with a gestation period between 22-25 days. A female G. holbrooki, on average, can have nine such broods during the breeding season. These eastern gambusia females give birth to young juvenile mosquitofishes, which mature in about two months. Since the mosquitofish give birth to young ones instead of laying eggs, these fish species are known as livebearers.

Environmental factors such as water temperature play a vital role in the body size growth and the reproductive maturity of this fish species.

What is their conservation status?

The conservation status of this species is Least Concern. Though native species of Florida and other south-eastern parts of America, this species was introduced by humans in Australia and other parts of the world with the idea of mosquito control. But this species soon became invasive and started affecting the populations of native fish species because of its aggressive nature, high adaptability, and fewer natural predators. In addition, the high breeding and high survival rate of juveniles have led to a massive increase in the populations of the species.

Eastern Mosquitofish Fun Facts

What do eastern mosquitofish look like?

The Eastern gambusia (G. holbrooki) is silvery on the belly, green to brownish on the top with a bluish sheen on the sides. These native fishes of the United States have an upturned mouth, large eyes, flattened heads, a single dorsal fin, and rounded caudal fins. The anal fin in females is similar to the dorsal fin, whereas the anal fin of males is pointed and known as a gonopodium. Their populations could be seen usually in freshwater ponds, lakes, and rivers.

Eastern mosquitofish (Gambusia holbrooki) is a freshwater fish and can adapt to saline conditions.

How cute are they?

Though it is small and appealing, many people do not find it cute because of its noxious status as a pest throughout Australia and many other western countries and its aggressive behavior towards other aquatic fish species.

How do they communicate?

The exact information on how these invasive species communicate with each other is not available. It is safe to assume that it communicates in the same ways as other fish species via sound, color, body gestures, and movements.

How big is an eastern mosquitofish?

Male eastern mosquitofish are about 1.3 in (3.5 cm) in length, and females are about 2.3 in (6 cm) in length. Even though small in size, they can attack fishes double their size due to their highly aggressive and invasive nature.

How fast can an eastern mosquitofish swim?

The exact speed with which this invasive species moves is unknown. But being aggressive, it is known to move very fast while competing for food with other native fish species. It moves well in shallow pond water or other shallow water sources.

How much does an eastern mosquitofish weigh?

The exact weight of this invasive mosquitofish is unknown. However, newborns of this species weigh very little. So we can assume that an adult's weight won't be more than a few ounces owing to its small size.

What are the male and female names of the species?

There are no particular names for male and female species. However, the male is known as male eastern mosquitofish, and the female is now as female eastern mosquitofish.

What would you call a baby eastern mosquitofish?

Like any other fish species, the baby of Eastern mosquitofish is known as a fry or a juvenile eastern mosquitofish. It takes about 18 days to eight weeks for this juvenile to become an adult. Its growth is dependent on water temperature and other factors. Colder temperature delays their maturity, and higher temperatures speed up the process. It is essential to keep these juveniles away from the adult Eastern gambusia species in captivity as they can cannibalize their babies.

What do they eat?

This Florida native likes to eat small insects, fish, algae, tadpoles, eggs, detritus, and mosquito larvae. It is capable of eating 500 mosquito larvae in a day! In captivity, it likes to eat flake food and frozen or live foods like bloodworms and shrimps. Mosquitofish compete for food with other fish species and hence have threatened the survival of other species when this invasive species was introduced into their natural habitat for mosquito control.

Are they dangerous?

The eastern mosquitofish is quite aggressive and capable of harming other fishes like fancy guppies or any fish with long delicate fins. They are excellent swimmers and can compete with other slow swimmers in the habitat for food, making the other species starve. They are voracious eaters and can eat frog eggs or tadpoles, which is why the yellow-spotted tree frog and golden bell frog species in Australia are becoming Critically Endangered. This invasive species has been dangerous to other native water species and has brought them into the Vulnerable category.

Would they make a good pet?

They can be good pets for those who like to keep exotic varieties. Because of their aggressive behavior and noxious reputation as an invasive species, they are rarely seen in aquariums. Western mosquitofish species are more commonly available in the pet market than the eastern G. holbrooki species. They require a minimum of 10 gal (37.9 l) tank with fresh water with a PH range between six to eight and water temperature ranging between 50-84°F (10-28.9°C). They can be housed with small minnows but should be kept away from long-finned fancy fishes like goldfish or guppies. Regular filtering of water is required to keep the fish healthy. G. holbrooki loves to eat mosquito larvae, small insects, and algae. In captivity, they can be fed fish flake food and other varieties of live or frozen foods like bloodworms and shrimp.

Did you know...

The eastern mosquitofish is considered one of the world's hundred most invasive species.

Are guppies and mosquito fish the same thing?

Both guppies and mosquitofish prefer freshwater habitats and are livebearers. They both are capable of cannibalizing their young ones. The anal fins in males are modified into gonopodium in both species, and the females have a dark spot on their bellies during pregnancy.

They come with a big list of differences too. For example, guppies are more colorful when compared to mosquitofishes. Mosquitofish is highly adaptable, and the PH of the water is not so important for it, but guppies prefer hard to very hard water with many minerals in it. Mosquitofishes are not very sociable with other fishes, and it is best to keep them with their kind in an aquarium. On the other hand, guppies can be kept with other livebearers without any issues.

Are mosquitofish invasive?

Mosquitofishes are highly invasive species. This species was introduced in the natural habitats of Australia with the idea of controlling the mosquito population. However, because of their aggressive fin nipping habit and voracious eating habit, they have started threatening many native species of Australia, for example, rainbowfish, green and golden bell frog species.

These mosquitofishes have also caused algal blooms in many ponds and lakes as they killed the fish species which used to feed on these algae. This has led to a decrease in water quality leading to changes in the biodiversity of that area.

Gambusia mosquitofish is considered a pest in Australia, and the government of Australia is taking various measures to control its spread.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! Learn more about some other fish from our ornate butterflyfish facts and pumpkinseed sunfish facts pages.

You can even occupy yourself at home by coloring in one of our free printable eastern mosquitofish coloring pages.

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