The Banded Allotoca: Habitat, Characteristics and Conservation

The banded allotoca is a small fish that isn't very popular because it's endemic to a Mexican river. It needs to ensure its conservation in its natural environment.

Written and verified by the biologist Georgelin Espinoza Medina.

Last update: 21 December, 2022

The fish of the family Goodeidae belong to 18 genera and 49 species. They’re freshwater fishes and, in general, found in limited places in Mexico. Among the members of this group, you can find the banded allotoca, a small fish that’s losing its fight for survival. Have you heard of it?

The scientific name of this fish is Allotoca goslinei and, although we know little about it, we’ll bring you what we do know. Read on and find out about its habitat, description, biological makeup, and conservation status.

Habitat and distribution of the banded allotoca

The banded allotoca is endemic to Mexico, particularly to the Potrero Grande stream in Jalisco, which is a tributary of the Ameca River. This means that its population is restricted to that particular geographic area, which automatically makes this species vulnerable.

The habitat of this fish includes shallow freshwaters no more than 1 meter (3.3 feet) wide and 20 centimeters deep (8 inches). It generally prefers clear or low-turbidity, calm water bodies with temperatures of between 16 and 20 °C. The substrates can be sandy, rocky, or muddy.

Physical characteristics

The banded allotoca has an elongated appearance and has very distinct body sections: head, trunk, and tail (or caudal fin). Like all other fish, it also has other types of fins, which are the following: dorsal, pelvic, pectoral, and anal.

The dorsal fin has the particularity of being located in the back of the body, next to the pelvic pair, almost at the end of the anal fin. This fish also has a series of pores in the region near the eyes, operculum, and jaws whose number helps identification.

Size

This species is small, like other members of the family. It’s usually no more than 50 millimeters (2 inches) in length in fully developed adult specimens.

Color

The coloration of the banded allotoca isn’t very bright and has a pattern of distinctive stripes (from which they derive their name). These lines are numerous, dark, accentuated, irregular, and tend to divide in two. They’re located at the base of the dorsal fin or near it.

Sexual dimorphism

The banded allotoca has sexual dimorphism, that is, females and males are different in some of their physical characteristics. In this case, they differ in size, the length of the dorsal fin, and the presence of certain spots on the body.

The female sex tends to be larger and has a shorter dorsal fin. Males, on the other hand, have a smaller body size and a longer dorsal fin. Males also have a lobe located behind the anal fin, which is used for copulation.

Skipjack behavior

Little is known about the behavior of these fish, but we know that they prefer calm waters, with abundant algae and floating aquatic plants. They usually stay in the shallow part of the water bodies below these plant organisms.

Feeding

Curiously, this small fish has a mouth apparatus consisting of two rows of teeth in its jaw, an outer row with cone-shaped and larger pieces, and an inner row with smaller ones. These structures allow it to carry out a carnivorous diet, as it consumes very small (but live) prey

Aquatic invertebrates are its most common victims. They can also include in their menu some animals from the surface, such as insects found near water or in vegetation.

Reproduction of the banded allotoca

All species of the family are viviparous, which means that the embryos are fully developed inside the female. Some data related to reproduction are the following:

• The newborn are only 9 to 12 millimeters long (0.5 inches).
• The female has been observed to have between 15 and 20 young.
• In captivity, these fish reach sexual maturity around 3 months after birth.

Conservation status of the banded allotoca

A few decades ago, the banded allotoca was a busy fish in its environment. Unfortunately, in recent years, there has been a decrease in the number of individuals and, since 2005, no specimens have been found in the wild.

The situation is alarming, which is why, in 2019, the IUCN  (International Union for Conservation of Nature) classified this specimen in the red list as “extinct in the wild”. There are only a few captive populations in certain parts of the world (Mexico, United States, and Europe).

Threats

Although it may seem strange, this species of allotoca isn’t attractive enough for collectors nor human consumption. However, it has a major threat in the locality where the fish is endemic, as it has fallen victim to an invasive animal that isn’t native to that region: the swordtail fish.

It’s estimated that this intrusive fish competed for the resources of the river and has so far won the battle against the banded allotoca, as its populations are increasing. Imagine having an invader in your house that takes away your food. Annoying, isn’t it? Well, that’s exactly what has happened to this little fish.

In summary, the banded allotoca is a freshwater fish endemic to Mexico that has been displaced and is extinct in its natural habitat. It’s important to know about the aspects related to its biological makeup and reproduction in order to improve captive breeding and thus prevent this animal from disappearing completely from the planet.

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