Like all darters, the fountain darter is actually a member of the family
Percidae, the perches. The darter is mottled brown in color for camoufl age, with dark markings along its sides and dark spots at the base of the tail, opercule, dorsal fin, and around the eye (Gilbert 1887; Schenck and Whiteside 1976). A spawning male will show more attractive markings. It is listed as endangered by TPWD and USFWS.
Usually less than an inch in length but can reach up to two inches in length.
Comal Springs and San Marcos aquatic ecosystems. Fountain darters require
clear, clean, fl owing waters of a constant temperature, adequate food supply, undisturbed
sand and gravel substrates, rock outcrops, and areas of submerged vegetation for cover
(Schenck and Whiteside 1977; McKinney and Sharp 1995; USFWS 1996). Young fountain
darters are found in heavily vegetated areas with slow moving water while adults can be
found in all suitable habitats (Schenck and Whiteside 1976). The present population of
fountain darters in the San Marcos River is well established; however, the fountain darter
population in the Comal River has been erratic. Numerous fountain darters were collected
in the Comal River in 1891, but between 1973 and 1975, biologists were unable to collect
any. This indicated that fountain darters no longer existed in the Comal aquatic ecosystem.
The most probable causes of the extirpation were the fi ve months the Comal Springs
ceased fl owing in 1956 during the prolonged drought, the extensive use of rotenone
by TPWD during this period, or a combination of both. In 1975, biologists from Texas
State University—San Marcos used fountain darters taken from the San Marcos River to
successfully reintroduce the species to the Comal aquatic ecosystem (USFWS 1996).