Barred Splitfin

Barred Splitfin, Chapalichthys encaustus

The Barred Splitfin, Chapalichthys encaustus, whose common Spanish name is pintito de Ocotlán, is a member of the Splitfin or Goodeidae Family, known collectively as mexclapiques in Mexico. Globally, there are three species in the genus Chapalichthys, which are all endemic to the freshwater systems of Mexico.

The Barred Splitfins have overall rectangular bodies that taper anteriorly to a pointed snout and posteriorly to a rectangular caudal peduncle. Females have a dusky-white background, a dark brown line mid-body that is discontinuous posteriorly, dark mottling dorsally, and numerous randomly spaced smaller brown spots ventrally; their anal and caudal fins are pale orange-red and their other fins are dusky. Males are silvery and shinny with a whitish background; they are covered with large brown oval spots mid-body, smaller more densely packed brown spots dorsally, and a yellowish-orange tinge with numerous randomly spaced small brown spots ventrally. The dorsal fin in males is dusky and their other fins have yellow margins. Their head has a small terminal mouth that projects upward and is equipped with bifid teeth. They have a short pointed snout with large eyes set on the midline. Their anal and dorsal fins are set well back on the body. Their caudal fin is square to slightly rounded. They have 20 to 28 slender gill rakers.

The Barred Splitfins are found demersal at depths up to 5 feet in clear, turbid, and muddy slow-moving freshwater bodies including lakes, ponds, streams, springs, and outflows over clay, gravel, mud, rocks, sand, and silt substrates that are lightly vegetated and have water temperatures between 16oC (60oF) and 28oC (83oF). They are reported to reach a maximum length of 9.3 cm (3.7 inches) with females being slightly larger than males. They are herbivores and consume primarily vegetable materials including green algae, water plants, microcrustaceans, and mollusks as well as flying insects. Reproduction is viviparous and involves internal fertilization followed by a short gestation period. Each female gives birth to numerous live young.

In Mexican waters the Barred Splitfins have a limited distribution and are found in the freshwater systems within the Mexican Plateau in west-central Mexico, such as in the Lerma River in the states of Jalisco and Michoacán, which is part of the Pacific drainage. They have also been documented via introduction in San Juan del Río, which is part of the Atlantic drainage in the State of Querétaro in north-central Mexico.

The Barred Splitfins are a popular fish with freshwater aquarists. From a conservation perspective they are currently considered Endangered. They have disappeared from several known sites and are now found only in a few small and isolated locations. They suffer from a lack of regular monitoring and historical site-specific population data. The water habitat in some parts of their range has experienced a staggering amount of degradation during the 20th century. They are heavily preyed upon by various birds and recently introduced non-native fish including Black Bass, Guppies, Sunfish, and Tilapia.

Barred Splitfin, Chapalichthys encaustus, Female.
Fish caught in a small lake within the Mexican Plateau in west-central Mexico, Michoacán, February 2017. Length: 7.5 cm (3.0 inches). Catch, photo, and identification courtesy of Ben Cantrell, Peoria, IL.

Barred Splitfin, Chapalichthys encaustus, Female. Fish caught in a small lake within the Mexican Plateau in west-central Mexico, Michoacán, February 2017. Length: 7.8 cm (3.1 inches). Catch, photo, and identification courtesy of Ben Cantrell, Peoria, IL.

Barred Splitfin, Chapalichthys encaustus, Male. Fish caught in a small lake within the Mexican Plateau in west-central Mexico, Michoacán, February 2017. Length: 7.5 cm (3.0 inches). Catch, photo, and identification courtesy of Ben Cantrell, Peoria, IL.

Barred Splitfin, Chapalichthys encaustus, Female. Fish caught in a small lake within the Mexican Plateau in west-central Mexico, Michoacán, February 2017. Length: 8.7 cm (3.4 inches). Catch, photo, and identification courtesy of Ryan Crutchfield, Tampa, FL.