The western mosquitofish 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 is also referred to by these names.
The eastern mosquitofish is a species of freshwater fish, closely related to the western mosquitofish, Gambusia affinis. It is a member of the family Poeciliidae of order Cyprinodontiformes. The eastern mosquitofish is native to the eastern and southern United States from Florida to Pennsylvania and inland to Alabama and Tennessee, while the western mosquitofish has a larger distribution throughout the United States.
Freshwater fish are those that spend some or all of their lives in fresh water, such as rivers and lakes, with a salinity of less than 1.05%. These environments differ from marine conditions in many ways, especially the difference in levels of salinity. To survive fresh water, the fish need a range of physiological adaptations.
The dusky millions fish, speckled mosquitofish or the one-spot livebearer is a species of fish native eastern and southern Brazil, northern Argentina, Uruguay and Paraguay. It has also been introduced to Australia, Malawi and New Zealand; primarily for mosquito control, but also as escapees from the aquarium trade. It has been reported as having adverse ecological effects in areas where it has been introduced. The females of this species grow to a total length of 6 centimetres (2.4 in), while males remain smaller.
Klerkskraal Dam is a combined gravity and arch type dam located on the Mooi River, near Ventersdorp, North West, South Africa. It was established in 1969 and its main purpose is to serve for irrigation. The hazard potential of the dam has been ranked high (3). The dam is also a well known bass fishing destination in the region.
The eastern mosquitofish was introduced to Australia in 1925, and had spread from the northeast coasts to New South Wales, southern Australia, and parts of Western Australia by 1934. By the 21st century, known populations of wild mosquitofish had occurred in every state and territory except the Northern Territory, found in swamps, lakes, billabongs, thermal springs, salt lakes, and ornamental ponds. Mosquitofish are considered a noxious pest, especially in New South Wales and Queensland, and it is illegal to release them into the wild or transport them live into any of the states or territories. Mosquitofish were introduced by military and local councils to control mosquito populations; however, there has been no evidence that Gambusia has had any effect in controlling mosquito populations or mosquito-borne diseases. Studies have shown that Gambusia can suffer mortalities if fed only on mosquito larvae, and survivors show poor growth and maturation. Gambusia typically eat zooplankton, beetles, mayflies, caddis flies, mites and other invertebrates; mosquito larvae make up only a small portion of their diet.
J. Stewart Smith was a British New Zealand man known for releasing several species of invasive freshwater fish into the country's waterways. A self-proclaimed Communist, Smith's goal was to introduce the coarse fishing of his childhood to New Zealand, which originally only had small native galaxias and introduced trout to fish for. Over the course of several decades, Smith would smuggle in fish and breed them in his garage in Massey, before releasing the offspring into rivers and lakes all over North Island. Due to his actions, the ecology of New Zealand's freshwater ecosystems has been permanently altered.
