Barred Splitfin

Barred Splitfin

Chapalichthys encaustus (Jordan & Snyder, 1899)

Also known as: Pintito de Ocotlán

Max Size: 6–8 cm TL (males smaller; females larger; up to ~9.3 cm SL reported)

A robust, rectangular-bodied goodeid with a pointed snout and solid, slightly rounded caudal peduncle. Males are silvery and shiny with a whitish ground color, large brown oval spots along the mid-body, denser smaller brown spots on the back, and a yellowish-orange tint with scattered small brown spots on the belly; their fins often show yellow margins. Females are dusky-white with a dark mid-body line (often broken toward the rear), dark mottling on the upper body, and numerous small brown spots below; their anal and caudal fins are pale orange-red. The classic goodeid “splitfin” (notched anal fin) is present in males. Both sexes have bifid teeth suited to their feeding style.

Origin & Habitat Endemic to west-central Mexico, primarily the lower Río Lerma, upper Río Grande de Santiago, and especially Lake Chapala and nearby lakes/ponds (La Luz, Orandino, Los Negritos, Cajititlán) in Jalisco and Michoacán. It inhabits quiet to slow-moving shallow waters (usually <1–1.3 m) of lakes, ponds, springs, and river channels over silt, mud, clay, sand, or rock, with sparse to moderate vegetation (algae, water hyacinth, Scirpus). Water temperatures range from about 16–28 °C; the water is often turbid to muddy.

Diet Primarily herbivorous. The long, coiled gut, bifid teeth, and numerous slender gill rakers point to a diet of algae, aquatic plants, and aufwuchs, though it also takes microcrustaceans, mollusks, and occasionally flying insects (sometimes leaping from the water to catch them).

Behavior & Temperament Peaceful demersal fish that does well in groups. It occupies the lower to middle levels of the aquarium and appreciates open swimming space with some plant cover or vertical structure.

Reproduction Viviparous livebearer with internal fertilization. Gestation is relatively short; females produce numerous live young.

Conservation Status IUCN: Vulnerable (VU).

Once abundant in nearshore areas of Lake Chapala and adjacent rivers, the barred splitfin has declined sharply due to severe pollution, habitat degradation, water-level drops, and competition/predation from invasive species (including poeciliids, tilapia, and bass). It has disappeared from parts of the mainstem Lerma and Santiago rivers but persists in reduced numbers in Lake Chapala and stronger populations in a few nearby lakes and spring-fed ponds (e.g., Los Negritos, Orandino/Verduzco dams). Lake Chapala is a Ramsar site, but targeted conservation actions remain limited.

A solid, attractively patterned Mexican endemic whose vertical barring and yellow-orange fin accents make it a distinctive addition to goodeid collections — and a species whose remaining strongholds deserve ongoing attention.