Studfish are in the fundulidae family (topminnows and killifish) and the males are definitely studs with their colorations. The two studfish I’ve seen the most are the Northern Studfish, Fundulus catenatus, and the Southern Studfish, Fundulus stellifer. The hard part is remembering which is which, but there is one obvious physical characteristic to tell them apart (other than where you are geographically). Both of the Northern and Southern Studfish have light sides that can be blueish in hue (more so on the Northern) with beautiful orange-red dots scattered all over the body. The main physical characteristic to tell them apart is how the dots are arranged along the body: Northern Studfish’s dots are in straight, horizontal lines, while the Southern Studfish’s dots are scattered randomly. I came up with a little saying to help me remember after I misidentified some of the DNR Stream Team photos: Northern = Neat, Southern = Sloppy.
LEFT: Southern Studfish which has randomly assorted dots along the body.
RIGHT: Northern Studfish which has dots that form horizontal lines down the body.
To add to the studfishes’ beautiful colorations, they also have hints of fluorescent green around their heads that becomes more noticeable during mating season. My favorite part about their interesting appearance is their superior mouth. You can tell a lot about a fish by the shape of it’s mouth. Fishes with superior mouths feed at the surface. Both of these species of studfish feed on insects at the surface, but have also been recorded consuming snails. Both of these studfish prefer clear, shallow water in streams, and tend to stay within the pools. These fish are easier to spot when exploring creeks because they stay at the surface.
The other main difference between these two species of studfish are their distributions throughout Georgia. The Northern Studfish is only found in the Tennessee river basin and is a state rare species. The Southern Studfish is found throughout the Coosa and Chattahoochee river basins and is more common. The best time to see a colored up male is during the mating season which for Southern studfish is late spring – early summer and Northern studfish is all summer.