Starhead Topminnow
Fundulus dispar

Description:  Starhead Topminnows are small freshwater fish.  Their backs and sides are olive-colored and they have lighter-colored cream or white bellies. They have a black teardrop-shaped spot underneath each eye.  The top of the head is flattened. Males have reddish-brown dots in vertical lines along the sides of their bodies; females instead have 7-9 horizontal lines on each side of the body.   
Size:  The Starhead Topminnow can reach a maximum of 6 cm
(2.3 inches) in length.

Individual animal information:  Cosley Zoo possesses a small group of topminnows, which were obtained from Milwaukee County Zoo in 2008.

Adaptations: 

• As their name implies, topminnows 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.
• If they are placed in an unfamiliar location, Starhead Topminnows will attempt to navigate back to familiar waters using the position of the sun as a guide.  On overcast days, they are not able to navigate as well.

Diet:  In the wild, Starhead Topminnows consume insects, crustaceans, mollusks, and some plant material.  At Cosley Zoo, the topminnows are given fish flakes, bloodworms and glassworms (insect larvae), and brine shrimp.

Reproduction:  Starhead Topminnows lay eggs between mid-April and mid-July.  Eggs hatch 9-11 days after being laid.  Females can produce multiple clutches (groups of eggs) per year.

Shelter and space needs:  These fish are found in slow-moving waters with a lot of vegetation, such as lakes, swamps and marshes.  The vegetation provides protective cover for the fish as well as a breeding ground for the insects they consume.  In Illinois, they are found in and around the Mississippi River.

Life expectancy:  2-3 years.

Relationship with man:  Topminnows are predators of mosquitoes, are often used for fishing bait, and are often kept in home aquariums. In nature, topminnows are particularly vulnerable to pollution such as oil spills because of their habit of feeding at the water’s surface. The Starhead Topminnow is a threatened species in Illinois.

Fun facts:

• Starhead Topminnows will sometimes leap out of the water to chase insects that are trying to escape!