Reintroducing Zoogoneticus tequila, the tequila splitfin


THE EXTINCTION OF SPECIES THROUGHOUT THE WORLD has been dramatically increasing, mainly due to different anthropogenic activities that affect ecosystems—the most important being the introduction of non-native species, habitat modification, and pollution. Here we describe our efforts to slow the extinction trend by successfull reintroducing an extinct-in-the-wild native fish species back into its natural habitat. We describe the steps we followed and the challenges we had to overcome, and we hope that our project can help inspire and guide fish reintroduction efforts elsewhere. In most cases, the recovery of a species from the brink of extinction, including reintroduction of extinct-in-the-wild species, has mostly focused on big, colorful, and charismatic species. Freshwater fishes are generally not the most charismatic species and frequently are forgotten in conservation initiatives. However, all species are important in the ecosystem.
Matthew W. Pedersen, Michael J. Tuccinardi,
Stephan M. Tanner, Ph.D.
EDITOR-IN-CHIEF | Friedrich Bitter
DESIGNER | Michael Kolmogortsev
EDITORS-AT-LARGE | Eric Bodrock, Gary Elson, Hans-
Georg Evers, Dr. Tim Hovanec, Ted Judy, Lawrence
Kent, Ad Konings, Gary Lange, Dr. Paul V. Loiselle,
Oliver Lucanus, Ingo Seidel, Greg Steeves, and Dr.
Michael Tobler
TRANSLATOR | Mary Bailey
ART DIRECTORS | Amey Radcliffe, Stephanie Salmon
DESIGNER | Anne Linton Elston
Aquatic Media Press, LLC
Stephan M. Tanner, Publisher
3075 Rosemary Lane NE
Rochester, MN 55906
Matthew W. Pedersen, Publisher
BUSINESS MANAGER | Susan Tuccinardi
ADVERTISING SALES | Michael J. Tuccinardi, Publisher
Janine Banks
NEWSSTAND | Howard White & Associates, Inc.
Dartmouth, MA
PRINTING | Dartmouth Printing, Hanover, NH
Call toll-free: 800-217-3523
AMAZONAS™, Freshwater Aquariums & Tropical
Discovery Copyright ©2020 by Aquatic Media Press, LLC
is published bimonthly in December, February, April, June,
August, and October. Periodicals postage paid at Rochester,
MN and at additional entry offi ces.
POSTMASTER: Send address changes to:
Aquatic Media Press, LLC, 3075 Rosemary Ln NE,
Rochester, MN 55906-4535, USA
SUBSCRIPTION RATES: U.S. $29 for one year.
Canada, $41 for one year. Outside U.S. and Canada,
$49 for one year.
ISSN 2166-3106 (Print) | ISSN 2166-3122 (Digital)
AMAZONAS is a licensed edition of AMAZONAS
Germany, Natur und Tier Verlag GmbH, Muenster, Germany.
All rights reserved. Reproduction of any material from this
issue in whole or in part is strictly prohibited.
COVER: Río Agua Azul, Chiapas, Mexico Photo by John
Lyons; tequila splitfi n (Zoogeneticus
tequila) Photo by Oliver Lucanus;
spot cheek cichlid (Thorichthys
maculipinnis ‘Río de la Lana’)
Photo by Uwe Werner Wolf
Reintroducing Zoogoneticus tequila, the tequila splitfi n
by Arely Ramírez-García, Gerardo García, Michael Köck,
John Lyons, and Omar Domínguez-Domínguez
by John Lyons
the Lacantún River in southeastern Mexico
by Norman Mercado-Silva, Nestor Rosales Quintero,
and Carlos Ramírez Martínez
Elegance in redThorichthys maculipinnis
by Uwe Werner Wolf
On the Mexican border: Trekking into the desert
for pupfi shes
by Roman Burkardt
A visit with crayfi sh breeder Markus Güsgen
by Ute Dederer and Friedrich Bitter
Newly described—the tiger limia, Limia islai
by Paul V. Loiselle
Taking a shine to shiners—Pteronotropis species
from the southeastern USA
by Friedrich Bitter
On the move: the glowlight danio, Danio choprae
by Ute Dederer
Going back to Peru for tetras
by Hans-Georg Evers
Upcoming events by Janine Banks
Reintroducing Zoogoneticus tequila,
the tequila splitfin
by Arely Ramírez-García, Gerardo
García, Michael Köck, John Lyons,
and Omar Domínguez-Domínguez
Good news is hard to come by
amidst the barrage of reports of
extinctions, habitat destruction,
and pollution from around the
world. But, in Mexico, one species
is back from the brink.
THE EXTINCTION OF SPECIES THROUGHOUT THE WORLD has been dramatically increasing,
mainly due to different anthropogenic activities that affect ecosystems—the most
important being the introduction of non-native species, habitat modification, and
pollution. Here we describe our efforts to slow the extinction trend by success-
fully reintroducing an extinct-in-the-wild native fish species back into its natural
habitat. We describe the steps we followed and the challenges we had to over-
come, and we hope that our project can help inspire and guide fish reintroduction
efforts elsewhere.
In most cases, the recovery of a species from the brink of extinction, including
reintroduction of extinct-in-the-wild species, has mostly focused on big, colorful,
and charismatic species. Freshwater fishes are generally not the most charismatic
species and frequently are forgotten in conservation initiatives. However, all spe-
cies are important in the ecosystem.
Endemic Species Under Threat
Goodeids are a biologically and ecologically interesting group of fishes, with
the entire subfamily Goodeinae endemic to Central Mexico. The subfamily has
unusual reproductive characteristics. All species are livebearers with internal
fertilization and matrotrophy, the ongoing provisioning by the mother to the
developing embryos. The males need to convince the females to copulate, so the
males of most of the species show a complex courtship and are more colorful than
the females. The females have modified ovaries to maintain embryo development
during gestation, and the embryos have a specialized structure, the trophotaenia,
that permits nutrient, waste, and gas transfer between females and embryos. Forty
Opposite page top: Professor
Rubén Hernandez and his
students taking water and aquatic
macroinvertebrates samples in the
spring at the reintroduction site at
the headwaters of the Teuchitlán
River. The barrier separates the
spring from the modified pool
used by the local people as a spa,
but they are connected by gates
that allows water to pass through.
Photo: Omar Domínguez
Opposite page bottom: Attractive
male tequila splitfins have a yellow
to orange margin on the caudal,
yellow on the outer edges of the
unpaired fins, and spangled
scales. Photo: Oliver Lucanus
Above: The headwater springs
flow out of the spas and
downstream into the Teuchitlán
River on the other side of the
concrete barrier and water gates.
Photo: Omar Domínguez
species of Mexican goodeids have been
described. Two species are likely extinct
with no captive populations, and three
species are probably extinct in the wild but have at least
one captive population in Mexico, the United States, or
Europe. Of the 35 extant species, 9 are considered as
critically endangered, 14 as endangered, 9 as vulnerable,
and only 3 as least concern by the International Union
for the Conservation of Nature (IUCN).
By Mexican Laws (NOM-059-SEMARNAT) the
goodeids are also cataloged as 17 species in danger of
extinction, 4 species as threatened, 1 probably extinct in
nature, and 1 suggested for special protection. The tequila
splitfin (Zoogoneticus tequila) (cataloged as endangered by
IUCN and NOM-059-2010) and the golden skiffia (Skif-
fia francesae) (cataloged as extinct in the wild by both),
each used to live in the upper part of the Ameca basin in
the Teuchitlán River.
This river is only a few kilometers long and used to
have high fish species richness and endemicity, with
12 native species of which four were found nowhere
else in the world. However, human impacts in the area
have been strong, including dam construction, water
extraction, municipal and industrial pollution, and the
introduction of exotic species. These impacts have caused
a major modification of the aquatic ecosystem and the
extirpation of several populations, pushing some of the
endemic species to extinction, including Z. tequila and S.
francesae, which were native to a single location.
The Fish Ark
In 2014, we began the recovery of the Teuchitlán ecosys-
tem and fish fauna, starting with a project to reintroduce
locally extinct fish species back into the Teuchitlán River,
beginning with the goodeid Z. tequila. The endeavor
was conducted as part of the Fish Ark Project, which
has more than 20 years of experience in Mexican fish
conservation and where 36 species of endangered and
extinct-in-the-wild species of goodeids have been kept
in captivity. The Fish Ark facility in Universidad Michoa-
cana de San Nicolás de Hidalgo, in Morelia has been
supported by several national and international conser-
vation organizations. It has also benefited from collabo-
ration with many dedicated aquarists from around the
world who have shared their knowledge and experiences
of maintaining rare species and helping to keep them
from extinction.
The original stock of Z. tequila was brought back to
Mexico by the enthusiastic English aquarist Ivan Dibble
in 1998 and was maintained in the Fish Ark since that
time. The reintroduction stock came from this ex-situ
facility where other extinct species are also maintained in
hopes that they, too, can someday be used for reestablish-
ment in the wild.
We planned the Z. tequila reintroduction project to
be conducted in several phases. The first phase was to
establish and maintain a large fish population in the Fish
Ark facility under the most natural conditions possible.
To this end, we built and managed an earthen pond in
the vicinity of Morelia where 80 specimens of Z. tequila
were introduced in 2012. Here, the fish were exposed
to semi-natural conditions: the water parameters and
food availability followed the natural seasonal cycle, and
predators (e.g. birds and snakes), parasites, and potential
competitors were present.
By 2016, we estimated that the pond had a population
of around 10,000 individuals. Even though our original
captive population was descended from just 4 pairs col-
lected in the 1980s and maintained in aquariums for
more than 30 years, we found that they were fully capable
of surviving, reproducing, and growing in “natural condi-
tions”. Now we were ready to begin the reintroduction
process. In our semi-captive population, we also conducted
Right and opposite page top left: Natural
springs form the headwaters of the Teuchitlán
River. Two pools fed by these springs, where
the tequila splitfin was reintroduced, have been
modified for human recreation. Barrier walls
with water gates separate the popular spa at
Balneario el Rincón with the river, allowing the
flow of water between them. Despite the springs’
unnatural appearance, the water is connected
to the river (shown on the previous page) and
conditions are good for aquatic life, including
the reintroduced tequila splitfins and other
native and introduced species.
Photos: Arely Ramírez
investigations to understand population parameters, feed-
ing habits, parasites, reproduction, life cycles, and other
aspects, looking for information that could facilitate our
actions and decisions during reintroduction.
Field Studies
At Teuchitlán, the first two years of the project were
focused on understanding the environmental and
ecological conditions of the area where the species was
to be reintroduced. We conducted several studies on
the diversity and populations of zooplankton, phyto-
plankton, invertebrates, fish, and parasites that lived
in the area. With this information and what we had
learned from the semi-captive population, we were able
to hypothesize about the possible interactions, both
positive (food sources) and negative (competition),
with the biotic and abiotic conditions at Teuchitlán. The
habitat surveys showed that the entire river was rich in
phytoplankton, zooplankton, and invertebrates, with
the greatest abundance in the lower part of the river,
and that the benthic invertebrates were dominated by
non-native species.
In fact, non-native fish species were more abun-
dant than native species and were most common in
the lower reaches of the river. Our studies indicated
that two-spot livebearer (Pseudoxiphophorus bimacu-
latus) was the most abundant non-native species in
the river and had a high competition potential with Z.
tequila. Habitat quality was better in the upstream part,
although the aquatic vegetation was more abundant
in the middle and downstream portion, and planted
habitats are preferred by Z. tequila. Parasites did not
appear to be a risk for the fish populations, being about
average in prevalence compared to other freshwater fish
communities in Mexico. Overall, downstream reaches
had more potential food for the reintroduced Z. tequila
population, but upstream had better habitat quality and
lower abundance of non-native fish species. We decided
that the upper parts of the river, including the springs
in its headwaters, were the best place to reintroduce
Z. tequila. We also concluded that non-native species,
in particular, the two-spot livebearer must be reduced
before reintroduction.
Preparing the Founder Population
The next steps involved hard work in the semi-captive
population as well as in the Teuchitlán River. In the
semi-captive population, the founder source for the
specimens that were to be reintroduced, we had found
one species of parasite, the nematode Spiroxys sp. larva,
and since we did not want to reintroduce any patho-
gens to the Teuchitlán River, we had to deworm all of
the specimens that were to be reintroduced. First, we
tried commercial treatments used in the aquarium
hobby, but we found that the recommended doses were
lethal for Z. tequila. Next, we tried natural deworm-
ing treatments such as garlic, epazote, and other plant
derivatives, with good results, but with an efficiency of
less than 80 percent. Finally, with metronidazole and
praziquantel we achieved 100 percent efficiency. Now,
we were capable of securing enough specimens for
reintroduction, free of parasites, and adapted to semi-
natural conditions.
What next? Before starting the full-scale reintro-
duction, we decided to conduct mesocosm experiments
in situ in the river to see how the fish would do under
natural river conditions. We first introduced 40 fish
each into four cages of 140 cubic feet (4 m3), 160 fish
in total in the upper part of the Teuchitlán River. We
found high mortality at the beginning of the experi-
ment, but by the end, the caged populations were grow-
ing, demonstrating that they were able to survive, feed,
grow, and reproduce.
Concurrent with the mesocosm experiments, we
were able to successfully reduce the numbers of non-
native fishes, removing about 2,500 fishes from the
Above: At the reintroduction site, a sign
informs visitors that the El Rincón spring
protects Ameca splendens (butterfly
goodeid), a fish exclusive to Teuchitlán. It
asks visitors not to use soap, catch, or feed
the fish. Photo: Arely Ramírez
planned re-establishment area with traps. We were
nally ready to start the reintroduction!
Enlisting the Locals
We decided to begin the reintroduction on the Day of
the Dead, November 2, 2016. This is a very important
cultural day for the Mexican people, when it is tradi-
tionally believed that loved ones who have departed to
the afterlife will come back again to spend the night
with their relatives who are still alive, with both groups
showing affection for each other in different ways.
Reintroducing Z. tequila on the Day of the Dead was
symbolic and was made as a kind of representation of a
beloved species that went away many years ago and that
was now coming back from extinction to spend a whole
lifetime with us. We felt that this symbolism would
resonate among the citizens of the town of Teuchitlán
along the banks of the river and emphasize how we were
trying to save this species from the clutches of total
extinction. To make this species more accessible to the
townspeople, we christened it “Zoogy”. At the same
time as we reintroduced Zoogy, we also reintroduced
another species that had disappeared, the Ameca shiner,
Notropis amecae.
Into the Wild
The headwater springs of the Teuchitlán River at the
reintroduction site have been modifi ed for human use
and are used as a spa. People go there to have their feet
and body exfoliated (cleaned) by native fi sh, and the
local people have the belief that the water is medicinal
and helps to keep skin healthy.
Despite this shared use, the water quality variables
in the springs are suffi cient to maintain viable fi sh
populations, including native species Goodea attripinnis,
Zoogonetcus purepechus, Ictalurus dugesii, and even en-
demic species, such as Ameca splendens. Gates between
the river and springs maintain the adequate water level
in the pools. During the project, larger gates were built
with fi sh traps so that water can fl ow out of the pools/
springs, but exotic species from the river can not enter
the springs.
The fi rst reintroduction consisted of 80 specimens,
all individually marked. After two months, only 36
specimens could be found, but six months later we
encountered 114 specimens, and half of the females were
pregnant. Fifty-fi ve percent of the fi sh were unmarked, in-
dicating that successful reproduction had already begun.
Once the process was underway, we studied the
newly wild population and tried to answer several ques-
tions: What do Z. tequila eat in their natural habitat?
How often do they reproduce? Is Z. tequila a host for any
wild parasite? How does Z. tequila interact with its neigh-
bors and with the habitat? Over the next three years,
we conducted a complete monitoring program of the
reintroduced population and its habitat. We found that
the population initially grew quickly but then began to
stabilize. In the fi rst two years after release, the popula-
tion grew at an annual rate of around 50 percent, indi-
cating that the population doubled. But in the fi nal year
of monitoring (2019), the population growth rate had
decreased to 25 percent indicating that the population
was beginning to level off. This decrease in growth rates
would be expected in a population that was stabilizing
Acclimation of Zoogoneticus tequila individuals, before their
reintroduction to the Teuchitlán springs. Left to right: Luis Martin
Mar, Gerardo Ochoa, Yvonne Herrerias, and co-author Arely
Ramírez. Photo: Bernardo Del Valle
and suggests that the Z. tequila population is coming into
balance with its environment in the springs.
Our data also indicated that the reintroduced
populations of Z. tequila had a wide range of sizes and
that the fi sh were in good condition and eating well.
Males ranged from 16–27 mm (0.7–1.1 inches) standard
length (SL), with most fi sh from 20–23 mm (0.8–0.9
inches). Females ranged from 18–30 mm (0.7–1.2
inches) SL with most fi sh 22–26 mm (0.9–1.0 inches).
Both sexes reached maturity at about 23 mm (0.9
inches) SL. Gonadal stage analysis showed that most
individuals (around 45 percent) were juveniles and that
mature adults represented 15 percent of the population.
Mature females had an average of four embryos. Female
reproduction peaked from February to April and then
decreased from June to August. Males had a reproduc-
tive peak during April which then decreased during June
and then increased again until August. A body condition
factor analysis indicated that Z. tequila was robust and in
good health throughout the year. Parasites did not seem
to be a problem with a general parasite prevalence of
only 3 percent and a low average abundance (0.009) and
intensity (0.33). Zoogoneticus tequila proved to be a gen-
eralist carnivore in the springs, feeding on 11 items, the
principal prey being the amphipod Hyallela (37 percent),
copepods (29 percent), and insect larvae (specifi cally
chironomids; 19 percent).
Water quality at the reintroduction site has re-
mained stable during the fi ve years of monitoring. The
mean annual water temperature has ranged from 72.5–
83.7°F (22.5–28.7°C). The pH (6.3~6.9) indicates
slightly acidic water, with the highest but still moderate
electrical conductivity at the downstream sampling site
near the La Vega Reservoir. The springs had the great-
est transparency, which then decreased downstream.
Dissolved oxygen concentrations ranged between 3.5
mg/L downstream and 6.1 mg/L upstream. Chlorophyll
showed its minimum value of 0.6 μg/L in the springs
and its maximum value of 10.7 μg/L downstream near
the La Vega Reservoir. Total hardness values indicated
that the water was soft.
Foundation for the Future
One of the most important tasks in conservation and
natural sciences is the transfer of knowledge and ideas
to society that can further advance the sustainable
development and conservation of natural resources. We
have started to build local capacities to secure the long-
term conservation of the Teuchitlán River and the native
sh species that live there, Ameca splendens, Zoogoneticus
purhepechus, and Goodea atripinnis (blackfi n goodea),
the reintroduced Z. tequila, and Notropis amecae (Ameca
shiner), as well as other species that we are planning
to reintroduce, such as Skiffi a francesae (golden skiffi a).
The butterfl y splitfi n or goodeid
(Ameca splendens), such as this
male, is also endemic to the
Teuchitlán River.
Photo: Andrzej Zabawski/
Meetings with the local government have been carried
out to provide a comprehensive plan for an environmen-
tal education program for adults and kids. This program
has been implemented and has effectively conveyed the
importance of the fi sh and aquatic environment in the
Teuchitlán area to its future development. We have been
also working, in cooperation with local people and the
government, to establish a natural reserve in the area.
The springs of the Teuchitlán River are once again
the home of Z. tequila, and the species is reproducing,
feeding, and interacting with native and non-native
species. When you have a chance to come to Mexico,
we invite you to visit Teuchitlán and take your snorkel
and dive into the springs to see this wonderful reintro-
duced species. We challenge you to fi nd its beautiful
orange caudal fi n! Welcome back Zoogy! Now it is time
to focus on the next species to be reintroduced to the
springs, Skiffi a francesae!
This project was led by the researchers and students at Uni-
versidad Michoacana de San Nicolás de Hidalgo, Morelia,
Mexico and sponsored by Chester Zoo Garden, Cheshire,
England; The Mohammed Bin Zayed Species Conservation
Fund, Abu Dhabi; Haus des Meeres-Aqua Terra Zoo, Vienna,
Austria; Poecilia Scandinavia, Norway; Poecilia Netherlands;
The Missouri Aquarium Society; Deutsche Gesellschaft für
Lebendgebärende Zahnkarpfen, Germany; British Livebearer
Association; Goodeid Working Group; American Livebearer
Association; The Mexican Commission for the Knowledge
and Use of Biodiversity; Association Beauval Nature Pour
la Conservation et la Recherche, France; and Wilhelma Zoo,
Stuttgart, Germany.
It is easy to determine the sex of
tequila splitfi ns. Males (below)
have the trademark orange band
on the tail, while females (above)
have clear fi ns.
Photos: Loury Cédric/France-
HERE, Esri | Natural Earth, Esri
0220 km
0135 mi
Mexico City
Puerto Escondido Huatulco
Melaque/Barra de Navidad Casimiro
Puerto Vallarta
San Blas
Cabo San
Pacific Ocean
Gulf of
Gulf of California
ResearchGate has not been able to resolve any citations for this publication.
ResearchGate has not been able to resolve any references for this publication.