Fish
Fish
Guppy (Millions)
Poecilia reticulata
The Guppy, known locally as "millions" for its explosive breeding, is a tiny livebearing fish native to Trinidad and Tobago streams that has become one of the most widely studied animals in evolutionary biology and one of the world's most popular aquarium fish, exported globally for the pet trade.
The Guppy, known locally as "millions" for its explosive breeding, is a tiny livebearing fish native to Trinidad and Tobago streams that has become one of the most widely studied animals in evolutionary biology and one of the world's most popular aquarium fish, exported globally for the pet trade.
Identification
A small fish rarely exceeding 3 to 6 cm, with males far smaller and more colourful than females, displaying variable, often iridescent patterns of orange, black, blue, and metallic spots used in courtship display, while females are larger, plainer, and silvery-grey. Colour patterns vary enormously between individual streams and even between pools within the same stream.
Ecology
Livebearing, giving birth to free-swimming young rather than laying eggs, and capable of extremely rapid population growth in still and slow-moving streams, ponds, and ditches, the source of the "millions" nickname. Trinidad's guppy populations, which vary systematically in male colour pattern and body shape between high-predation stream reaches (downstream, sharing water with predatory fish) and low-predation headwater reaches (upstream, largely predator-free), have made the species one of the classic model systems for studying natural selection and rapid evolutionary change in the wild.
In Trinidad and Tobago
Native and abundant in freshwater streams and ponds across both islands; the Northern Range streams of Trinidad are the source population for decades of globally influential evolutionary research on the species, including experimental studies that have physically transplanted guppies between high- and low-predation stream reaches to observe evolution occurring in real time.
Threats
- Habitat degradation of native streams
- Genetic mixing with released aquarium strains
