Barrens topminnow

Naming

''F. julisia'' is not only found in one state, Tennessee, but also in only one region, the Cumberland Plateau. In that specific region it is currently only found in the Elk River and a drainage creek of the Cumberland River, West Hickory Creek. However, that has not always been the only thought of location for ''F. julisia's'' habitat. They are often associated with springs, but drought conditions made them adapt to survive in springs where permanent water was near by. They prefer heavily vegetated areas of aquatic vegetation or algae in shallow, slow moving water. Given the above habitat, it is observed that ''F. julisia'' can tolerate warm temperatures of water and turbidity, the presence of competitors, and the presence of predators. This, along with spawning, make aquatic vegetation a limiting factor for the fish.

Distribution

''F. julisia'' is not only found in one state, Tennessee, but also in only one region, the Cumberland Plateau. In that specific region it is currently only found in the Elk River and a drainage creek of the Cumberland River, West Hickory Creek. However, that has not always been the only thought of location for ''F. julisia's'' habitat. They are often associated with springs, but drought conditions made them adapt to survive in springs where permanent water was near by. They prefer heavily vegetated areas of aquatic vegetation or algae in shallow, slow moving water. Given the above habitat, it is observed that ''F. julisia'' can tolerate warm temperatures of water and turbidity, the presence of competitors, and the presence of predators. This, along with spawning, make aquatic vegetation a limiting factor for the fish.

Habitat

In overall behavior ''F. julisia'' does not differ greatly from other members of the ''Fundulus'' genus. It is an opportunistic carnivore that preys upon crustaceans, gastropods , and insects that are both aquatic and that fall into the substrate. In an examination of gut contents it was found that crustaceans made up 64% of their diet while aquatic insects made up 23% and various other organisms made up the remaining 13%. It competes for this prey with ''Fundulus catenatus'' and ''Gambusia affinis'' . This is an interesting relationship because ''G. affinis'' is one of the leading causes of decline in ''F. julisia'' due to competition for the same prey. ''F. julisia'' is preyed upon by bass and sunfish within the substrate. Outside the water ''F. julisia'' is preyed upon by piscivorous birds that spear them with a sharp tipped beak or catch them with ridged edged beaks. During breeding season males are easily spotted due to their bright mating colors, which makes them easier prey. Males have been found to have two different morphs with the primary difference being the marginal and submarginal bands on the caudal and posterior dorsal fin. One morph has a pale yellow submarginal band and the other translucent blue with white and orange submarginal band. All females are far less colorful appearing yellowish and washed out. Even as juveniles males and females can be distinguished from one another due to the males having an iridescent green coloration on their sides.

Evolution

Breeding season for this species is annual and is believed to be as early as mid-March when the males were observed to first have their breeding colors. At this time the water temperature is roughly 14-15 C. Eggs have been collected in mid-April from clumps of algae. Females lay around 200-250 mature ova over a period time, laying only a few daily. Though relatively opportunistic in spawning sites, ''F. julisia'' egg morphology suggests that submergent vegetation is most preferred and in turn most successful. Loss of successful spawning sites could be one of the main ecological factors that limit its distribution. Territoriality has been observed in the field, but it is more abundant in aquaria settings. In aquaria males have been observed defending portions of the tank that resulted in a single male's dominance. In the field males only slightly defend their clumps of filamentous algae. Females never exhibited territorial behavior in the field, but were seen defending feeding areas in the aquaria. Sexual maturity is reached at 1 year with a maximum lifespan of 3 years, though most individuals do not live that long and die off after spawning.