Tilapia as exotic species

Capable of establishing themselves into new ponds and waterways, many tilapia have escaped aquaculture facilities across much of Asia, Africa, and South America.

In doing so, tilapia often out compete native fish, create turbidity in rivers by digging, and can reduce available sun light for aquatic plants.

These early introductions of tilapia were intended to act as a form of biological control, combating the growth of weeds and proliferation of mosquitos.

[10] As early as 1979, there were established populations of spotted tilapia (Pelmatolapia mariae) and convict cichlid (Amatitlania nigrofasciata) in the cooler climate of Victoria; in a pond warmed by a power station.

[10] By 1991, waters surrounding the Queensland cities of Brisbane, Townsville, and the Gascoyne River in Western Australia were filled with Mozambique tilapia (Oreochromis mossambicus).

Native fishes, invertebrates, and other organisms have experienced a reduction in stream access and cover as a result of tilapia activities.

[15][16] In 2017, spotted tilapia were found extending their range northward into warmer waters, in a tributary of the Mitchell River, with the potential to affect important barramundi and prawn fisheries in the Gulf of Carpentaria.

The Mozambique tilapia (Oreochromis mossambicus) is known as "Mujair" in Indonesia, having received its name from Moedjair who introduced this fish in the Serang River on the southern coast of Java in 1939.

In addition, hybrids classified as O. niloticus may have inherited a diminished tolerance for saline conditions, thus restricting the environments in which tilapia can be found.

[23][24] Other tilapia, including redbelly, are present in nearby waters, but no longer able to survive the high salinity in the Salton Sea itself.

Today, ancient remnants of fish species that once lived in Lake Cahuilla can still be unearthed in the Salton Sea basin.

Fossil evidence of fish species include machete (Elops affinis), bonytail (Gila robusta), and stripped mullet (Mugil Cephalus).

[28] In addition to polychaete worms, adult tilapia regularly feed upon phytoplankton, copepods, smaller fishes and barnacles.

High salinity concentrations, algal blooms, agricultural runoff, hypoxia, wind events and temperature variability all contribute to fish die-offs in the Salton Sea.