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Common gambusia, lat. Gambusia affinis


Order: Cyprinodontiformes;
Family: Poeciliidae;
Genus: Gambusia;
Species and synonyms: Common gambusia (Gambusia affinis, Western Mosquitofish).

GBIF: Gambusia affinis (Baird & Girard, 1853)

Common gambusia (lat. Gambusia affinis) is a species of livebearing ray-finned fish from the order Cyprinodontiformes, family Poeciliidae, genus Gambusia. The fish is known for its ability to feed on mosquito larvae, which led to its widespread introduction around the world for malaria control.

Distribution. The natural range of gambusia covers the Mississippi River basin from central Indiana and Illinois south to the Gulf of Mexico, as well as coastal areas west to Mexico. Due to targeted introduction for mosquito control, the species has achieved near-global distribution and is found in freshwater bodies of Asia, Africa, Australia, Southern Europe and other regions.

Care requirements. Gambusia is one of the most undemanding aquarium fish. For keeping a small school (20–25 specimens), a 60-liter aquarium is suitable. Optimal water temperature: 20–26°C, hardness: up to 25 dGH, pH: 6.0–8.0. Filtration is required, salting of water (up to 5 g/L) is permissible. Gambusia are omnivorous: they eat dry flakes, live and frozen foods, as well as mosquito larvae. They are active, stay in the upper and middle water layers, prefer aquariums with dense vegetation. Females reach up to 7 cm in length, males up to 4 cm. Adult fish may nip the fins of slow-moving tankmates, so they are not recommended to be kept with veiltail forms of fish. Lifespan is up to 3 years.

Gambusia are livebearers with internal fertilization. They reach sexual maturity at 2–3 months of age. Pregnancy lasts 20–25 days, the female gives birth to up to 60 fry. Adults eat their young, so to preserve offspring, the female should be placed in a separate container with shelters. Fry are fed brine shrimp nauplii, microworms and fine dry food.

Gambusia against malaria on the Black Sea coast. At the beginning of the 20th century, the Black Sea coast of the Caucasus was a malaria-endemic region: according to various estimates, the incidence ranged from 40 to 60 percent, and in some areas reached 90 percent. The marshy terrain and abundant swarms of malarial mosquitoes made the development of the resort region impossible.

In 1925, on the initiative of epidemiologists Nikolay Rukhadze and Sergey Sokolov, work began on the introduction of gambusia to the Black Sea coast of the Caucasus. The first fish were brought from Italy, where experience in breeding these larvivorous fish had already been established. Initially, gambusia were released into puddles and ponds of Sukhum, and then distributed throughout Abkhazia.

The voracity of gambusia is impressive: a single fish can eat up to 300 malarial mosquito larvae per day. At the same time, gambusia proved to be extremely hardy: it can withstand temperatures from 0 to 43 degrees, can winter under ice and tolerate water salinity of up to 7 percent — twice as much as in the ocean. It was precisely these qualities that allowed gambusia to successfully acclimatize in the region's water bodies.

By 1956, not a single case of malaria was recorded in Sochi — this year became the first in the city's history without the disease. In the 1960s, malaria was almost completely eradicated along the entire Black Sea coast of the Caucasus. Thanks to this, Abkhazia and Sochi turned into prestigious all-Union resorts.

As a sign of gratitude to the little fish-savior, a bronze monument to gambusia was erected in the Adler district of Sochi in 2010. Today, the Sergey Sokolov Ecological and Biological Center continues to breed gambusia and distribute it free of charge to citizens for the prevention of tropical infections.

At the same time, the introduction of gambusia also has negative consequences. Due to its aggressive behavior and omnivorous nature, this fish can eat the eggs and fry of native species, nip the fins of other fish, and disrupt the biodiversity of water bodies, which has made gambusia an invasive species in some regions of the world, such as Australia.