TankBud

Eastern mosquitofish

Gambusia holbrooki

Also known as Mosquitofish

FreshwaterFish

Eastern mosquitofish (Gambusia holbrooki)
JeffreyGammon · CC BY-SA 4.0

Care at a glance

Temperature
59–84°F
15–29°C
pH
6.5–8.5
Adult size
3.1 in
8 cm
Minimum tank
11 gal
40 L
Temperament
Aggressive
Social behavior
Social
Tankmates
With caution
Swim level
Top
Difficulty
Beginner
Breeding
Livebearer · Easy
Rarity
Common
Family
Poeciliidae
Origin
Atlantic and Gulf Slope drainages, eastern USA (New Jersey to Alabama)

Overview

The eastern mosquitofish is a hardy, aggressive livebearer that stays near the surface. It is easy for a beginner to keep, but its fin nipping limits the choice of tank mates.

Did you know

The eastern mosquitofish is named for its appetite for mosquito larvae, which got it shipped around the world for mosquito control. Its hardiness also made it one of the most damaging invasive fish on the planet. It outcompetes and nips native species wherever it gets loose.

Caring for the eastern mosquitofish

Keep eastern mosquitofish in 11 gal (40 L) or larger, which helps spread out the males' harassment. Plant the edges densely and give them plenty of cover near the top. They are active near the surface and spend most of their time there.

The water can run cool to warm, at 59 to 84°F (15 to 29°C), with a pH of 6.5 to 8.5. A heater is optional, and room temperature is fine. They also tolerate brackish water. Feed flakes, small pellets and frozen foods such as daphnia or brine shrimp.

Eastern mosquitofish are aggressive fin-nippers, so they are not peaceful community fish. Keep them away from long-finned or slow tank mates such as fancy guppies, bettas and goldfish. They do fine in a group of their own kind, with around one male to three females.

Most stay around 4 to 6 cm, and large females reach 8 cm, while males stay smaller at roughly 4.7 cm. Females give birth to 5 to 100 live fry per brood, with no parental care. They breed on their own with no effort, so expect fry fast.

This species is aggressively invasive and is banned or restricted in many places. Check your local rules before keeping it, and never release it into the wild.

Good to know

The eastern mosquitofish, Gambusia holbrooki, is a livebearer in the family Poeciliidae. It is also called simply the mosquitofish.

In the wild

Eastern mosquitofish come from slow streams, ponds and marsh edges in the eastern USA. Their range runs along the Atlantic and Gulf Slope, from New Jersey down to Alabama. They hang near the surface in warm, weedy shallows.

Common questions

What size tank does an eastern mosquitofish need?

An eastern mosquitofish needs at least 11 gal (40 L). It spends most of its time in the top.

What temperature and pH does an eastern mosquitofish need?

An eastern mosquitofish is comfortable at 59–84°F (15–29°C) with a pH of 6.5–8.5.

What does an eastern mosquitofish eat?

An eastern mosquitofish eats flakes, small pellets and frozen foods such as daphnia or brine shrimp.

How big does an eastern mosquitofish get?

An adult eastern mosquitofish reaches about 3.1 in (8 cm).

How can you tell a male eastern mosquitofish from a female?

Males stay smaller, at roughly 4.7 cm, while large females reach 8 cm.

How does an eastern mosquitofish breed?

Eastern mosquitofish are livebearers, and a female drops 5 to 100 live fry per brood with no parental care. They breed on their own with no effort.

Related species