About Fundulus chrysotus (Günther, 1866)
The golden topminnow, Fundulus chrysotus, is a native United States fish belonging to the genus Fundulus. It is mostly distributed across the southeastern United States, ranging from Kentucky and Ohio south into Florida. Even with this wide southern distribution, the habitats and microhabitats it occupies remain largely consistent across its range. Golden topminnow are small fish that feed at the water's surface. They tend to reproduce from late spring into early summer, and while their fry reach maturity fairly quickly, the species has a relatively short lifespan. As small fish low on the trophic level, they primarily feed on small or drifting organisms at or near the surface of vegetated areas. Currently, the golden topminnow is not listed as an endangered species, and no specific management plan exists for the species. The golden topminnow's geographic range covers the southeastern continental United States. Specifically, it inhabits the Santee River Drainage of South Carolina westward to the Trinity River Drainage of Texas, and can be found throughout the Mississippi Embayment north to Kentucky and Missouri. Further south, it lives in the Lower Coastal Plain and is widely scattered across Florida. It has also been documented extending northwest into the Gulf Coastal Plain of McCurtain County, Oklahoma, and Mississippi County, Missouri. Outside these core areas, the species is extremely localized and uncommon. The golden topminnow's diet ranges from aquatic plants to terrestrial invertebrates, but it consists mostly of aquatic invertebrates. A study of fish feeding habits in Lake Seminole, on the Florida-Georgia border, included observations of golden topminnow. The species was found to consume small amounts of aquatic macrophytes and a wider variety of aquatic invertebrates, including gastropods (snails and slugs), large quantities of ostracods (seed shrimp), ephemeropterans (mayflies), coleopterans (water beetles), and chironomids (non-biting midges). The golden topminnow's diet does not include vertebrate prey; the most common food sources are seed shrimp and midge larvae, with water beetles and mayflies as minor diet components. Due to its low trophic position, the golden topminnow is prey for a wide variety of predators that hunt small, surface-feeding vertebrates. These predators include, but are not limited to, largemouth bass (Micropterus salmoides), redear sunfish (Lepomis microlophus), bluegill sunfish (Lepomis macrochirus), and bluespotted sunfish (Enneacanthus gloriosus). The golden topminnow can tolerate a range of salinity levels. Experiments recorded a 100% mean survival rate at 7 and 14 percent salinity; survival dropped to 91% at 21% salinity, fell to 24% at 28% salinity, and reached 0% at 35% salinity. This tolerance range allows the species to survive and reproduce in the narrow range of salinities found in its native coastal and brackish water habitats. Major human impacts on golden topminnow populations include habitat pollution, and the conversion of marshlands and brackish water areas for agricultural use. Golden topminnow breed from spring through summer, between April and July, and sometimes as late as September. During courtship, the male swims in loops or circles above or beside the female, occasionally pausing to bob his head up and down. The female releases eggs individually, and deposits them on the roots of floating plants or other fibrous material; the male then fertilizes the eggs one at a time. After hatching, larvae rest on leaves or the bottom, and grow quickly to reach maturation after 10 months. Mature golden topminnow have a slender body, a rounded caudal fin, and a deep caudal peduncle. Their mouth is small and slightly superior, their dorsal fin is set far back on the body and starts posterior to the origin of the anal fin. They lack a lateral line, have 7–9 dorsal rays, 9–11 anal rays, 12–14 pectoral rays, and 6 pelvic rays. During the breeding season, males develop prickly contact organs on the side of the body between the dorsal and anal fins, on the ends of the last few dorsal rays, on the anal fin, and on the outermost pectoral fin rays. The life expectancy of the golden topminnow is approximately 2 years. Citation: Ross, S. T. 2001. The Inland Fishes of Mississippi. University Press of Mississippi, Jackson. 624 pp.
