Killifishes and Live-Bearers: Cyprinodontiformes

Physical characteristics: Blackfin pearl killifish are rarely more than 2 inches (5 centimeters) long. The fins are blue-black with shiny metallic-green borders. There are pearly whitish to greenish spots on all fins and the body.

Geographic range: Blackfin pearl killifish live in Uruguay and Argentina.

Blackfin pearl killifish live in Uruguay and Argentina. They are found in temporary waters, such as flooded meadows, shallow ponds, and roadside ditches. (Illustration by Emily Damstra. Reproduced by permission.)

Habitat: Blackfin pearl killifish live in temporary waters, such as flooded meadows, shallow ponds, and roadside ditches.

Diet: Blackfin pearl killifish eat insects, worms, and other water-dwelling invertebrates.

Behavior and reproduction: A male blackfin pearl killifish takes over an area that it defends against other males. A female moves in and signals she is ready to reproduce by tilting herself down. The pair spawns on the bottom of the pond or ditch. The eggs laid go into a resting state. When the water evaporates, the adults die, but the eggs survive and then hatch in the next rainy season, within hours of getting wet.

Blackfin pearl killifish and people: Blackfin pearl killifish are exchanged among aquarium hobbyists but are sold only rarely.

Conservation status: Blackfin pearl killifish are not threatened or endangered. ∎