Home / Fishes / Killifish and livebearers / Mosquitofish
No federal permit to keepMosquitofish
Gambusia affinis
Fishes › Killifish and livebearers (Cyprinodontiformes) › Poeciliidae (Livebearers)
The western mosquitofish (Gambusia affinis) is a North American freshwater poeciliid fish, also known commonly, if ambiguously, as simply mosquitofish or by its generic name, Gambusia, or by the common name gambezi.
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 1.5 in / 3.9 cm; the largest recorded was 2.0 in).
- Water: Freshwater (tolerates brackish).
- Temperature: 54–84°F (range recorded for this species).
- pH: 6–8.
- Hardness: 5–19 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: Eats a varied diet: mix quality prepared foods with frozen and live foods. FishBase classes it as a carnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 64–81 °F, pH 6–8, 5–30 dGH.
- Difficulty: Beginner (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “A gently-filtered, heavily planted setup suits it best.”
- Diet: “Unfussy and omnivorous, it will accept most foods offered.”
- Tankmates: “Not a good choice for the community tank.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Livebearers (guppies, mollies, platies and swordtails)
Applies to most species in this group. Habitat: Warm streams, ponds and brackish waters. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Planted tanks with gentle flow; mollies appreciate harder, slightly brackish water.
Diet
- Flake foods with plant matter, plus live or frozen foods.
Social life
- Peaceful community fish; keep more females than males.
Health watch
- They breed constantly; plan for fry or keep single-sex groups.
Understanding the animal
About this animal
About this animal
Its sister species, the eastern mosquitofish (Gambusia holbrooki) is also referred to by these names. Mosquitofish are small in comparison to many other freshwater fish, with females reaching a maximum length of 7 cm (2.8 in) and males a maximum length of 4 cm (1.6 in).
Quoted from the Wikipedia article “Mosquitofish” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater and brackish water, in rivers and streams, estuaries. Uses both the bottom and open water. Most abundant in lower reaches of streams. |
| Ground it lives on | Over mud, silt. |
| Water it lives in | Freshwater / brackish water, 54–84 °F (12–29 °C), pH 6–8, hardness 5–19 dH. |
| Climate | Subtropical climate. |
| Behavior to plan for | Breeding: internal live bearers, maternal parental care. |
What this means for care
- Keep water within its wild range, 54–84 °F.
- Use a soft, fine bottom; it lives over fine sediment in the wild.
- It tolerates or needs brackish water; check salinity needs before setup.
- Parents guard eggs or young, so expect territorial behavior when breeding.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 91°F (up to 96°F in the hottest sampled areas) |
| Cool-season lows | about 29°F (down to 16°F in the coldest sampled areas) |
| Average temperature | 51–70°F across sampled records |
| Relative humidity | 58–71% on average (driest month about 62%) |
| Rainfall | about 1011 mm a year, spread fairly evenly |
| Winters | Cool to cold winters (lows around 29°F) in much of its native range. Seasonal slowdown may be relevant, but species-specific biology determines whether brumation or hibernation occurs. |
Measured at 2484 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The western mosquitofish (Gambusia affinis) is a North American freshwater poeciliid fish, also known commonly, if ambiguously, as simply mosquitofish or by its generic name, Gambusia, or by the common name gambezi. Its sister species, the eastern mosquitofish (Gambusia holbrooki) is also referred to by these names. Mosquitofish are small in comparison to many other freshwater fish, with females reaching a maximum length of 7 cm and males a maximum length of 4 cm. The female can be distinguished from the male by her larger size and a gravid spot at the posterior of her abdomen. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Wild diet | Mosquitofish are diet generalists, but they are considered "larvivorous" because they consume the larvae of mosquitoes and other aquatic insects. Their diet consists of zooplankton, small insects and insect larvae, and detritus material. Mosquitofish feed on mosquito larvae at all stages of life, if mosquito larvae are available in the environment. — Wikipedia (community-edited) |
| Reproduction | The species is viviparous. Internal fertilization is possible because the anal fin of the male is modified into a copulatory organ. The females carries about 30 alevins and gestation lasts for a period of 24 days to a month. — FishBase |
| Appearance and size | Mosquitofish are small and of a dull grey coloring, with a large abdomen, and have rounded dorsal and caudal fins and an upturned mouth. Sexual dimorphism is seen; mature females reach a maximum overall length of 7 cm, while males reach only 4 cm. Sexual dimorphism is also seen in the physiological structures of the body. — Wikipedia (community-edited) |
| Biology | Most abundant in lower reaches of streams. Adults inhabit standing to slow-flowing water; most common in vegetated ponds and lakes, backwaters and quiet pools of streams. They are found frequently in brackish water. — FishBase |
| History and naming | The mosquitofish is a member of the family Poeciliidae of order Cyprinodontiformes. The genus name Gambusia is derived from the Cuban Spanish term gambusino, meaning "useless". The common name, mosquitofish, is derived from their use for biological control of mosquitoes, which itself was based on early observations that, in certain circumstances, they can reduce mosquito abundances. — Wikipedia (community-edited) |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Maximum recorded lifespan
Longest recorded lifespan reported by each database; typical lifespans are usually shorter.
Adult length
Common length to maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Female maturity
Veterinary & husbandry research
Veterinary & husbandry research
- Biological mosquito control is affected by alternative prey Kumar R et al., Zoological studies 2015
- Endocrine disruption in western mosquitofish from open and closed aquatic ecosystems polluted by swine farm wastewaters Huang GY et al., Environment international 2020
- The first record of Centrocestus formosanus (Nishigori, 1924) (Digenea: Heterophyidae) in Egypt Yousif F et al., Experimental parasitology 2016
- Immune-related genes expression analysis of Western mosquitofish (Gambusia affinis) challenged with Aeromonas hydrophila Liu S et al., Fish & shellfish immunology 2020
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. See all 24 on PubMed → 170
Sources for this sheet
- AnAge: The Animal Ageing and Longevity Database (Human Ageing Genomic Resources) Peer-reviewed researchCurated, referenced longevity and life-history records for thousands of species; maximum lifespans are often from zoo animals.
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Types and features of aquatic systems Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Nutritional diseases of fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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