Tired of mosquitoes feeding on you? Time to bring in an ally that will give them a taste of their own medicine. Mosquitofish are hungry little guys that love to snack on mosquito larvae. These finned friends are a natural pest control option for homeowners who can’t get rid of all standing water sources in their backyards. Here we bring you a complete guide to mosquitofish.
Mosquitofish Basics
What is a Mosquitofish?
Mosquitofish is the popular name for two small freshwater fish species belonging to the Poeciliidae family, namely the western mosquitofish (Gambusia affinis) and the eastern mosquitofish (Gambusia holbrooki).
Known for their ability to consume large numbers of mosquito larvae, mosquitofish are the most widespread freshwater fish in the world. Native to Central and North America, their origin is expressed in their name:
- The western mosquitofish (Gambusia affinis) originates from the Mississippi drainage basin, which spans from Kansas to southern Illinois in the north. In the southern extent of its distribution, it can be found in rivers that flow into the Gulf of Mexico, ranging from Mobile Bay to San Antonio Bay, as well as in inland drainages south of the Rio Grande.
- The eastern mosquitofish (Gambusia holbrooki) is native to the eastern coast of the United States. Its range stretches from Florida north and westward to southern Alabama, and extends northward along the Eastern U.S. to southern New Jersey.
In some states, their presence was caused by human intervention. Introduced to California in 1922 as mosquito control agents, mosquitofish were established within the state and then introduced to other regions such as Oregon, Washington, the Great Lakes, and even Hawaii.
Anatomy
Guppy-like, the physical appearance of the mosquitofish resembles the common minnow (Phoxinus phoxinus). Here are some of their physical characteristics:
- Color: Adult mosquitofish have an olive-green back with silvery sides and belly.
- Size: At birth, mosquitofish younglings are about 3/8 inches long. When adults, males are slender and about 1 to 1.5 inches long. The adult females are larger and more robust, ranging from 1.5 to 2.5 inches long.
The two species (G. affinis and G. holbrooki) were previously thought to be the same, but recently researchers found they are actually distinct species. They differ in the number of rays in each fin and the presence or absence of teeth on the male gonopodium (a modified fin used for reproduction).
| Dorsal fin rays | Anal fin rays | Teeth on the first gonopodial ray | |
| Gambusia affinis | 6 | 9 | Absent |
| Gambusia holbrooki | 7 | 10 | Present |
Natural Habitat
Mosquitofish have adapted to live in shallow, still, or slow-moving waters. They also occur in habitats with dense aquatic vegetation, which they can use both to hide from predators and feed on when they feel like eating a salad.
One of the key characteristics of mosquitofish is their flexibility and adaptability to different environments. Here are some of the habitat characteristics that mosquitofish prefer:
- Water temperature: Mosquitofish have a preference for temperatures around 80 degrees Fahrenheit, but they can endure temperatures as low as 33 degrees and as high as 104 degrees Fahrenheit.
- Water quality: These little guys prefer still, undisturbed lakes and swamps but can also survive in highly disturbed water bodies such as urban drains with high levels of pollution.
Life Cycle
Mosquitofish are live-bearing fish, which means that they do not lay eggs but give birth to live young. This is why they are commonly called livebearers. Each female produces three to four broods in her lifetime, each one with around 40 to 100 younglings, also called “fry.”
The gestation period varies between 22 to 25 days, but depending on the environment (including the water temperature and the season), this period can extend from 15 up to 50 days. Although she is able to produce broods throughout the year, the female usually gives birth during the warmer months of spring and summer.
Once out of the womb, the fry will immediately search for the nearest cover and start to feed. A mosquitofish’s lifespan is around a year.
Feeding Habits
The mosquitofish diet varies widely. These guys are hungry little fellas that will eat almost anything. Their upwards-facing mouths allow them to eat everything that stays on the water’s surface. They can feed on:
- Small insects
- Crustaceans
- Algae
- Small invertebrates
And, of course, they have a taste for mosquito larvae. An adult female mosquitofish can consume up to three times her body weight in mosquito larvae per day. For their larvae-eating capacities, they have been recommended by Vector Control Programs throughout the U.S. as a biological control measure against mosquitoes.
Mosquitofish Care
Now that you know the basics about mosquitofish, it’s time to talk about how to properly care for these little friends; however, there’s little to do since mosquitofish are amazingly easy to care for. Here’s how to prepare for your new backyard guests.
Housing
Mosquitofish can be used in a variety of bodies of water, as long as they are still or slow-moving. Here are some of the places where mosquitofish can be introduced:
- Ornamental ponds and fountains
- Out-of-use swimming pools and rain barrels
- Animal water troughs and birdbaths
Is there a place where mosquitofish cannot be used? Yes: You should never introduce mosquitofish in natural water sources such as creeks, lakes, or rivers. Because mosquitofish are incredible at adapting, they have easily become an invasive species in many ecosystems.
But besides their use in backyard ponds and birdbaths as mosquito control, mosquitofish can also be housed in aquariums.
Environment
Because of their extreme adaptability, mosquitofish can survive even the direst of environments: extreme temperature and salinity variations, low oxygen conditions, poor water quality, and so on. But of course, since you’re bringing them into your home, you’ll want to provide them with a cozy room.
Here’s how to create an environment your new mosquito-eating babies prefer and will thrive in:
- Care for their water: The ideal water temperature for mosquitofish is approximately 80 degrees. The ideal water pH is between 6.5 to 8.0. Do not use any chlorine or yard sprays in or near the water, as these substances can kill mosquitofish. If using tap water, treat it with a proper water conditioner (you can find it at local fisheries).
- Create refuge: Make sure you add aquatic plants and rocks they can use as a shelter. They are useful to hide from larger fish or outside predators (like birds or racoons). Also, keep an eye on algae overgrowth in the summer as it can cause fish kill.
- Add friends, not foes: Since we mentioned other fish, mosquitofish can either eat smaller fish or be preyed upon by larger fish. So ensure they are living alone or with other species they can get along with, like the common goldfish, koi fish, and carp.
- Ensure adequate space: The amount of mosquitofish you should get will depend on your available space. One fish per 2 to 5 gallons of water is a good rule of thumb. Three to five mosquitofish are enough if you plan on adding them to a pond with a surface area smaller than 200 square feet, for example.
Pro tip: When introducing mosquitofish to their new home, let them acclimate. Place the container you receive them in directly into their new environment and wait 15 minutes so the temperatures even out. Then you can release them into their new house.
Diet
Have I mentioned that mosquitofish are easy to care for? Well, this extends to their feeding as well. During warmer months, mosquito larvae are plentiful and enough for these little fellas to keep their tummies full.
You’ll only need to feed them during colder months or if their environment doesn’t have any aquatic vegetation they can feed on. In such cases, fish flakes twice a day will suffice.
Other Fish Species
Photo Credit: Bernat Arlandis / Flickr / CC BY-SA 2.0
Luckily, mosquitofish are not the only fish species that help to get rid of mosquitoes. A number of other native species can feed on mosquito larvae as well. If you’re looking for other options to help reduce mosquito populations, here are some other examples that can help us fight the mosquito battle:
- Sailfin molly (Poecilia latipinna) and killifish (Heterandria formosa), both native to Florida
- Eastern mudminnow (Umbra pygmaea), native to eastern North America
- Lined topminnow (Fundulus lineolatus), native from the southern region of Virginia to the Ochlockonee River in Georgia and Florida, and extending further south in Florida until reaching Lake Okeechobee
- Guppies (Poecilia reticulata), native to the Caribbean islands
FAQ
Vector Control districts commonly provide free mosquitofish to residents. You can check with your local program to request mosquitofish as a natural mosquito control method.
Mosquitofish are regarded as highly effective in controlling mosquito populations. But there is another point to consider. Because they are an aggressive species, if introduced into natural waterways, they can compete with other indigenous species that also act as mosquito control.
Mosquitofish invasion in natural waterways has been linked to the reduction of local amphibians and other fish species that also feed on mosquito larvae. Once they disrupt local ecosystems, their presence becomes counterproductive.
Yes, mosquitofish are very easy to keep. Once properly installed in their habitat, you will only have to worry about feeding during the colder months.
Gather Your Allies Against Mosquitoes
In the fight against mosquitoes, every little bit helps. And there’s only so much mosquitofish can do for us. If you’re in need of allies who can offer more than a hungry stomach, Pest Gnome connects you to the best pest control experts in your area. Get in touch today!
References:
Main Image Credit: mauribo / Canva Pro / License
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