Topminnows have a habit of skimming along just beneath the surface of the water, so the top of the head and forward part of the back are broad and flat, and the mouth is tilted upward so it opens at the upper surface of the head. The body is long, there is no lateral line, and the single dorsal fin is located far back over the anal fin. The tail fin is rounded. None of the fins have spines.
The blackstripe topminnow is light brown with a broad, black horizontal stripe along the midside. There is no dusky vertical bar beneath the eye. It has a wider black longitudinal stripe than its cousin, the blackspotted topminnow.
Total length: 2 to 3 1/2 inches.
Inhabits streams in southwestern and eastern Missouri where the closely related blackspotted topminnow is not found
Habitat and Conservation
Along large lowland rivers and in the pools of streams draining flatter uplands. Prefers slightly cooler and less turbid streams than the blackspotted topminnow.
Topminnows cruise along the upper surface of water, looking for invertebrates on the water surface. They feed most intensely in the morning, late afternoon and evening. About half the diet is terrestrial insects; the rest of the diet is aquatic insects, crustaceans, snails and algae (algae passes through the gut undigested).
Common in its range. It is more widely distributed in Missouri now than it was in the early 1940s, when it was restricted to the lowlands of southeastern Missouri, the Mississippi River and its tributaries along the eastern edge of the state, and the Neosho (Spring-Elk) system of southwestern Missouri. Its range has expanded since then, due to bait-bucket introductions and natural territory expansion.
Spawns in spring. Lives in pairs or small groups that cruise slowly along the shoreline. Most active in morning and evening.
Topminnows and other members of the killifish family are generally quite colorful and popular with aquarists.
Just as catfish are specially equipped for hunting along the bottom of the aquatic ecosystem, topminnows hunt in a special zone of water: the water surface, particularly along the shoreline. Both types of fish have adapted to use a part of the aquatic environment other fish don't.