Blackstripe Killifish
Fundulus notatus

Description:  The Blackstripe Killifish is a small, elongate freshwater fish.  This fish has a distinct black stripe running around each side of its body.  Its body and fins are an olive color, and its belly is white.  It can be identified from above by the white spot on top of its head.  The head is flattened on the top.  Males and females can be distinguished by the shape of their dorsal fins (on their backs) and their anal fins (on the bottom of the fish, close to the tail).  The males have longer, pointed dorsal and anal fins, while females’ fins are more rounded.

Size:  Blackstripe Killifish measure between 5 and 7 cm long
(2-3 inches).

Individual animal information:  Cosley Zoo possesses a small group of Blackstripe Killifish, which were obtained from Milwaukee Zoo, where they were hatched in 2008.

Adaptations: 

• Blackstripe Killifish usually stay near the top of the water in order to take advantage of the plentiful supply of insects and other food sources found there.

Diet:  In the wild, Blackstripe Killifish eat insects, insect larvae, small mollusks, spiders, and crustaceans.  At Cosley Zoo, these fish are given fish flakes, bloodworms and glassworms (insect larvae), and brine shrimp.

Reproduction:  Reproduction occurs between May and August.  Females lay 20-30 eggs at once.  The eggs are then fertilized and hidden away in vegetation by the males, hatching 10-14 days later.

Shelter and space needs:  Blackstripe Killifish inhabit areas of clear, slow-moving freshwater such as streams, rivers, and lakes.  In Illinois, they are found in and around the Mississippi River.  They prefer areas with some vegetation, which provides protective cover for the fish and a breeding ground for the insects they consume.  Although they stay near the water’s surface for most of the year, they do move to deeper water in the winter if the surface freezes over. 

Life expectancy:  Blackstripe Killifish can live approximately 2-3 years.

Relationship with man:  Blackstripe Killifish are predators of mosquitoes, are often used for fishing bait, and are easy to maintain in home aquariums. In nature, they are particularly vulnerable to pollution such as oil spills because of their habit of feeding at the water’s surface.