Guppy

Where it lives

Native to warm freshwater streams, ditches, and ponds across northeastern South America and the southern Caribbean, guppies have been introduced worldwide for mosquito control and through aquarium releases. They tolerate brackish water and a wide range of temperatures.

How to recognise it

Strong sexual dimorphism. Females are larger, plainer gray-tan fish. Males are tiny and vividly colored, with patches and spots of orange, red, blue, green, black, and metallic iridescence across the flanks and tail. Selectively bred fancy strains exaggerate fin shape and color into elaborate varieties.

Diet & behavior

Guppies are omnivorous grazers, picking algae, tiny crustaceans, mosquito larvae, and detritus. They are livebearers — fertilization is internal, and females release dozens of fully formed fry every three to four weeks.

Fisheries & Conservation

Globally Least Concern. Among the most-studied vertebrates in evolutionary biology, especially as a model for sexual selection and rapid local adaptation.