Banded Allotoca

Banded Allotoca

Allotoca goslinei Smith & Miller, 1987

Also known as: Tiro listado, Tiro rayado

Max Size: ~5 cm SL (up to about 6 cm TL)

A slender, elongated little goodeid whose sides are marked by 12–18 narrow vertical bars or blotches — the feature that gives it both its English and Spanish names. Males typically show a prominent dark elongate spot on the mid-side above the rear half of the pelvic fin (sometimes with one or two more spots farther forward), followed by irregular bars or blotches toward the tail; they also develop larger dorsal and anal fins and the classic goodeid “splitfin” (notched anal fin used for internal fertilization). Females are similar but usually display clearer striping on the caudal peduncle and three mid-side spots. Both sexes have conical teeth arranged in two rows, suited to a predatory lifestyle. Average adult lengths are roughly 32 mm for males and 34 mm for females.

Origin & Habitat Formerly endemic to a tiny area in the headwaters of the Río Ameca basin in Jalisco, Mexico — primarily the Arroyo (Río) Potrero Grande about 10 km west of the town of Ameca, and nearby sections of the Río Cuisillos near Presa La Vega. It lived in quiet to slightly flowing shallow pools (often only 15–26 cm deep) under floating plants such as water hyacinth and filamentous algae, over sand, gravel, silt, or mud substrates. Water was clear to murky, with temperatures typically 16–28 °C.

Diet Primarily carnivorous/insectivorous. Conical teeth indicate it hunted small invertebrates and surface insects. In aquariums it accepts high-quality flakes, granules, tablets, and live or frozen foods such as brine shrimp nauplii, daphnia, and bloodworms.

Behavior & Temperament Somewhat shy, preferring structured habitats with hiding spots from which it can observe its surroundings. Best kept in groups in well-planted tanks with moderate current and high oxygen levels. Peaceful toward other species of similar size.

Reproduction Viviparous livebearer with elongated-rosette trophotaeniae. Gestation produces relatively large young (9–12 mm at birth). Females can give birth to 15–20 fry. Sexual maturity is reached in about three months under good conditions. In captivity, a cool winter rest period helps regulate breeding.

Conservation Status IUCN: Extinct in the Wild (EW). Mexican NOM-059: En Peligro de Extinción.

This single Evolutionary Significant Unit (ESU Altgo1) was wiped out by water pollution in the main Ameca River by the 1990s and then rapidly eliminated from its last stronghold in the Potrero Grande by the early 2000s after the invasion of non-native green swordtails (Xiphophorus hellerii). The last confirmed wild individuals were seen in 2004; subsequent surveys found none.

Fortunately, small but stable captive populations survive in Mexico, the United States, and Europe (around 400+ individuals in coordinated holdings as of recent counts). The species is part of active conservation breeding programs (including Fish Ark Mexico and the Allotoca-Mesa Central project), with studbooks maintained and reintroduction efforts into restored habitats now under discussion and planning.

A delicately banded highland endemic that vanished from the wild almost as soon as it was scientifically described — yet still swims in dedicated aquariums and conservation programs, offering both beauty and a powerful reminder of how quickly Mexico’s unique goodeids can disappear.