German wasp | Vespula germanica

German wasp

Vespula germanica

Coral bush | Ardisia crenata

Coral bush

Ardisia crenata

Purple loosestrife | Lythrum salicaria

Purple loosestrife

Lythrum salicaria

Pom pom weed | Campuloclinium macrocephalum

Pom pom weed

Campuloclinium macrocephalum

Canarybird bush | Crotalaria agatiflora

Canarybird bush

Crotalaria agatiflora

Peanut butter cassia | Senna didymobotrya

Peanut butter cassia

Senna didymobotrya

Rubber vine | Cryptostegia grandiflora

Rubber vine

Cryptostegia grandiflora

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Environmental Programmes

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Mosquitofish

Gambusia affinis

Common name:

Mosquitofish

Scientific name:

Gambusia affinis

Alternative common names:

Western mosquitofish, gambezi, guayacon mosquito (Spanish). 

The mosquitofish is a species of freshwater fish indigenous to the Mississippi River in the USA. It is listed as one of the world’s worst invasive species. The name 'mosquitofish' was given because the diet of this fish predominantly consists of large amounts of mosquito larvae (as well as other invertebrate larvae); an adult female can consume hundreds in a day.

Additional Info

  • Where does this species come from?

    Eastern and southern United States of America.

    What is its invasive status in South Africa?

    NEMBA Category 1b in national parks, provincial reserves, mountain catchment areas and forestry reserves declared in terms of the Protected Areas Act. NEMBA Category 2 for breeding for the purpose of feeding stock for zoos and animal breeders. NEMBA Category 3 for all other discrete catchment system in which it occurs.

    Where in South Africa is it a problem?

    Sundays River Valley, Eastern Cape.

    How does it spread?

    Mosquitofish can be spread during floods and through unintentional relocation when it is inadvertently transported in aquatic equipment, such as nets, boats and fishing gear.

    Why is it a problem?

    Adults are extremely aggressive and attack other fish, shredding their fins and sometimes killing them. They are known to prey on eggs, larvae and juveniles of various fishes, including largemouth bass and common carp. They are also known to prey on adults of smaller species.

    What does it look like?

    Description: Mosquitofish is a small, live-bearing fish, dull grey or brown, with no bars or bands on the sides, and a rounded tail. The body is short and the head flattened, with the mouth pointed upward for surface feeding. It may have a large dusky to black teardrop marking beneath its eye, but this marking is sometimes reduced. Females have a rounded, small anal fin and grow to about 6-7cm. Males grow to about 4cm. Habitat: It occurs in a variety of freshwater and protected brackish environments. It preferentially occupies vegetated ponds and lakes, backwaters and quiet pools of streams. It is most often encountered in standing or slow-flowing waters. Breeding: Sperm transfer occurs when males insert their gonopodium in the oviductal opening of the female. Females can store viable sperm for several months. After fertilisation, young are born in about 24 days. Maturity occurs after one month for males and six weeks for females. The maximum age of mosquitofish is four years. They prefer temperatures between 12-29 degrees Celsius. However, in deep enough water they are able to reduce activity and go into a hibernation-like state.

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General News Updates

2019 National Symposium on Biological Invasio…

26-02-2019

This is your invitation to South Africa's 2019 National Symposium on Biological Invasions. The convention is hosted by the Centre for Invasion Biology (CIB), University of Stellenbosch, and the Biolo... Read more

2019 Invasive Species Training

22-01-2019

During the past five years (2014-2018), ISSA invasive species trainers have trained 4 000 in the identification of invasive species and laws pertaining to invasive species across South Africa.  ... Read more

Alien Grass Working Group

04-09-2018

Who are we? The South African National Alien Grass Working Group was jointly initiated by the South African Biodiversity Institute (SANBI) and the Centre for Excellence in Invasion Biology (C·I·B) in... Read more

Permits for planting indigenous Cynodon?

01-03-2018

On 16 February, 2018, South Africa's Department of Environmental Affairs issued amendments to the regulations and lists relating to the National List of Invasive Species.  Updates to the draft&n... Read more

Invasive species training 2018 dates released

28-02-2018

Interested in invasive species?  How much do you know about NEMBA invasive species compliance for landowners and organs of state? The South African Green Industries Council (SAGIC) have released... Read more

Communications post for Africa advertised

25-01-2018

The Nature Conservancy has advertised a brand new post:  Communications Manager, Africa Region. Knowledge of invasive species and water would be an asset in this post. See details below:    Job Titl... Read more