The splendid darter (Etheostoma barrenense) is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is endemic to the Barren River system in south-central Kentucky and north-central Tennessee. This species is usually found in small rocky pools on the sides of creeks and rivers. The splendid darter, like many other darter species, inhabits a single small river system and exhibits specialized reproductive behaviors that are only supported by a particular type of environment. This river system is vulnerable to even the slightest changes, whether natural or anthropogenic, putting inhabitants of the system at risk. The two most influential landscape features affecting the current distribution of E. barrenense are land use/land cover patterns and soil composition. As such, these two phenomena must be closely monitored in the following years to ensure the safety of the splendid darter and all other species found in the Barren River system. The current existence and continuing development of dams in Tennessee is one of the most pressing issues affecting freshwater environments and preventing many species of fish from migrating properly. Distribution The splendid darter is found only in the Barren River system of southern central Kentucky and northern central Tennessee; this system is a part of the Ohio River drainage. The range of this species is between 5000 – 20,000 square kilometers, which is relatively small. E. barrenense is not thought to have either spread or shrunk its distribution since it was described in 1982, but very little data are available on its dispersal and other movements; some larvae may drift along with the current, but ultimately, the species has remained in its small range. The splendid darter has a tendency to spend most of its life in deep, rocky pools and the riffles of small creeks and rivers, as well as streams. The geographic distribution of E. barrenense and other darter species is extremely important to the way the species passes on its genes to subsequent generations. Much of the isolation that remains between closely related species of darters is due to brilliant nuptial coloring and behavioral isolation, ensuring that mates of the same species are attracted to one another. Since many of these species live in sympatric populations, there must be a mechanism such as this, allowing the genes of different species to remain isolated. Without