1. Salmo trutta
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Salmo trutta |
Brown trout has been introduced into many cold water bodies around the world for fishing purposes and has now adapted and thrived in various locations. Brown trout have outcompeted and reduced populations of native fish species (especially other salmonids), amphibians, and invertebrates due to predation, habitat displacement, and food competition.
Common name: Brown Trout
2. Cyprinus carpio
This species of carp has been introduced into freshwater bodies worldwide for food and ornamental purposes. This carp species is considered harmful as it often quickly achieves high densities, stirring up sediments which reduce water clarity, and uprooting aquatic plants that serve as habitats for many aquatic organisms.
Common name: Common Carp
3. Micropterus salmoides
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Cyprinus Carpio |
Due to its delicious meat and appeal for sports fishing, the largemouth bass has been widely introduced around the world. This species is carnivorous, opportunistic, and hunts both day and night. Their diet includes fish, shrimp, amphibians, and insects.
Common name: Largemouth Bass
4. Oreochromis mossambicus
Mozambique tilapia has been popularized and introduced into many countries around the world for food cultivation. Adapted populations of this species in the wild are a result of intentional releases or escapes from farming operations. They are omnivorous, eating almost everything from algae to insects. They form dense populations, leading to food shortages in their habitats.
Common name: Mozambique Tilapia
5. Lates niloticus
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Lates niloticus |
The Nile perch was introduced into Lake Victoria in 1954, where it contributed to the extinction of over 200 native fish species due to predation and food competition.
Common name: Nile Perch
6. Oncorhynchus mykiss
Rainbow trout is a popular game fish species introduced into many rivers and lakes. They have rapidly adapted and threaten to eliminate native fish species by preying on larvae while also hybridizing with other salmon species, affecting their genetics. Furthermore, they compete with and displace other fish species from their habitats.
Common name: Rainbow Trout
7. Clarias batrachus
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Clarias batrachus |
This carnivorous catfish species originates from East Asia and was introduced to Florida in 1960 for aquaculture. Since then, this catfish species has adapted and thrived widely in the wild throughout Florida. During dry seasons, large numbers of this catfish may congregate in certain ponds and prey on local fish species.
Common name: Walking Catfish
8. Gambusia affinis
Introduced in many parts of the world under the mistaken belief that they are more effective at controlling mosquito populations than native species that feed on larvae, gambusia have been causing harm to aquatic ecosystems due to their voracious nature. The release of gambusia for mosquito control is still being carried out by some agencies combating malaria and other mosquito-borne diseases.
Common name: Gambusia, Mosquito Fish
(The species in this list are selected to illustrate the harmful effects of invasive species. The absence of species from this list does not imply they are less dangerous.)
