Cyprinodontiformes vivíparos e ovovivíparos

Livebearer Cyprinodontiformes

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Species > Species profile > Characodon audax

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I - Morphology Synopsis ( some meristic characters )

Total absolute length

Adult male : 32.0 to 49.8 mm

Adult female : 36 to 65.6 mm

Dorsal fin rays : / 9 ( 12 ) generally 9-11 ( females ), 11-12 ( males )

Caudal fin rays : / 17 ( 21 )

Scales on lateral line : 30 ( 34 )

Head length body length ratio ( male ) : 0,28

Head length body length ratio ( female ) : 0,21

You can find more pictures about these species available at the photo gallery.

II - Habitat and Geographical distribution

The single geographical location described for this species is situated in the State of Durango, Mexico.
The territory of this State occupies about 6.3% of the country ( the fifth largest in area ). Its capital city is located only some 80 km north the Tropic of Cancer, between Sierra Madre Occidental and the western part of the Mexican plateau.
Durango is surrounded by the State of Chihuahua at North, the States of Coahuila and Zacatecas at East, the State of Nayarit at South and the State of Sinaloa at West.
We are talking about a mountainous region, which includes about 160 kilometres of the Sierra Madre Occidental in the direction Northwest - Southeast.
In general, the climate is characterized to be mild but also extremely dry. As the altitude increases rainfall will become greater as the temperature decrease, becoming semi-cold in some points in the higher altitude.
Scientifically the region is divided into four climate categories; semi-hot sub-humid ( on the slopes of the Pacific Ocean ), temperate sub-humid or rainy cold at high altitude, semi-dry in the valleys and very dry in the semi - desert.
Taking in consideration the region around the identified site where the species is naturally established in particular, the climate is temperate sub-humid with average annual temperature of 16ºC ( 60,8ºF ) and a rainfall of around 500 to 600 mm.
The months of greatest rainfall are between May and October, with some chance of frost between September and April. In winter, freezing temperatures may occur during the winter nights, but in summer the maximum can exceed 35ºC ( 95ºF ).
On a hydrological approach, the State presents some river basins that drain toward the Pacific Ocean, on the western side of the Sierra Madre Occidental, and a smaller number of major river basins that drain toward the Atlantic, directly to the Gulf of Mexico on the opposite eastern side.
Some of the major rivers flow into lakes, particularly in semi-desert plateau.
In Durango we can also find quite abundant water sources ( springs ) with thermal and mineral-medicinal characteristics.
The only location currently known regarding this species natural distribution, is near the village of El Toboso and includes only a small spring “ El Baño de las Mujeres “ that feeds the “ Laguna del Toboso “ ( an ephemeral lake that only receives water from the water source during the most abundant rainfall and has recently dried out in several years ).
Curiously, the distance between “ Laguna del Toboso “ and the Mezquital river basin, where we can find the close species Characodon lateralis is only 50 meters ( Rio La Sauceda ).
Some authors defend the existence of a second location, but it as naturally been kept secret ( can it be in fact El Tobosito ? ).
In the article “ Mexican Goodeid Fishes of the Genus Characodon, with Description of a New Species “ the geographic coordinates of the type locality appear as “ 24°16'35 N lat., 104°34'50 W long. “, but searching for this place with the Google Earth engine, at these coordinates, there is no water body at all.
However, there are two possible locations near by, at 24º16'52.49" N / 104°34'50.05" W and at 24°16'33.54" N / 104°34'56.99" W, which may be the “ Laguna del Toboso “. According to the characteristics exhibited in several sources, perhaps the second hypothesis is the right one, but the former is more isolated.
Eventually neither water bodies marked are the accurate ones, as the town of Toboso appears only identified on this tool with another village, located 80 Km away, near Lake Chapala. Perhaps some of our visitors to this region of Mexico may one day help to unravel this mystery, if it would be proper.
From the descriptions found, the “ Laguna del Toboso “ is actually a small lake, with an area of approximately 1200 square meters of surface. Such water body is also characterized by its shallowness.
Inside the spring the ground is often muddy, but has several areas of sand. The depth is around only 20 centimetres.
This water oasis is set in a semi-desert area, which implies, naturally, a regular extraction of water for local people daily needs.
The Bold Characodon seems to be, according to the information achieved, the only existing fish species, although there have been identified some aquatic insects and one water turtle species ( Chelidra serpentine ) in the same habitat.
Usually the water on this lake is clear and the temperature on the spring is consistently 19ºC ( 66.2ºF ) all year round.
As there is practically no significant current, the authors have witnessing the emergence of abundant underwater vegetation, along with more or less abundant algae communities.
Aquatic plant species, described by the sources consulted are Ceratophyllum sp, Potamogeton sp, and Lemna sp.
If we consider that, apart from climate changes, the abundance of water and its purity is decreasing at the rate of local human population increase, the prospects for survival of the last refuges of this species are not encouraging, except in some hypothetical very isolated spot far from civilization.

III - Physical-chemistry parameters

Ideal temperature range : 19ºC ( 66.2ºF )

Tolerated limits : between 12ºC ( 53.6ºF ) and 27ºC ( 80.6ºF )

Survival limits : between 10ºC ( 50ºF ) and 29ºC ( 84.2ºF )

Ideal pH : 6.9 – 8

Ideal dH : 9º - 19º

Maximum salinity : ?

Temperature annual maintenance for this species in captivity ( suggestion ) :
 

IV - Biology and ecology synopsis

The lengthened ( elongated ) shape, very unusual among other species of the subfamily Goodeinae, as well as the placement of the dorsal fin, caudal and anal, all located very rear result on the most evident remote kinship with the ovuliparous Splitfins of the Empetrichthys and Crenichthys genus, but above all with Crenichthys baileyi .

The genus Characodon is even considered, by some researchers, as the most primitive genus on the sub-family Goodeinae.

In captivity, under the presence of other species, the Bold Characodon appears to be a fish somewhat reserved, but once in a single species aquarium, dedicated to him, this kind of behavior will soon change.

Disputes between males become common occurrences and natural shyness seems to conceal the display of some intra-specific aggression between members of both sexes.

Since this species inhabits near the pristine spring waters in the wild, according to my personal experience there is an evident advantage and best keeping results with daily renewal of at least 10% of the tank water, ( all depending on the capacity of the tank and effectiveness of its filtering ), although some fellow hobbyists advocate the opposite.

To avoid the known common side effects of this operation, particularly when made with tap water, you must perform the partial water changes only with a chlorine free reserve.

It is not yet scientifically proven, but many of the hobbyists that keep this species believe that the level of resistance to some diseases may be related to these water replacements ( or partial water changes, as we says in the jargon ). Keep however in mind that there is no consensus on this matter.

In fact there are many contradictory reports, some saying that this species is in fact an extremely hardy and resistant one, but many more anticipating frequent health problems.

Temperature may possibly be another factor influencing the health of this fish.

In the wild, although abundant in the near by spring, where the water temperature is roughly 19ºC ( 66.2ºF ) all year round, the fish can be spotted on the close basin of Laguna del Toboso, so keeping this species between 17ºC ( 62.6ºF ) and 23ºC ( 73.4ºF ) does not seem to bring any adverse consequences.

It is manifest that although the Bold Characodon tolerates higher temperatures, there are quite obvious benefits of maintaining the fish of below 26ºC ( 78.8ºF ) even in the warmest season of the year. All keepers seams to recognized the vital need for a more fresh seasonal period ( at least between 16ºC or 60.8ºF and 18ºC or 64.4ºF ).

During maintenance at lower temperatures, the reproductive cycle ceases and it is possible to observe a delay in growth rate, mainly in animals that have not yet reached its full development.

Unlike its relative, Characodon lateralis, the cold tolerance or the ability to cope with sudden drops on water temperature is not as good as expected. Unlike other fish from temperate regions, the ability to survive cold strikes is reduced, so they shouldn't be submitted to the lower tolerated temperatures other than for short periods of time.

Despite dawn drops to slightly negative values can be considered common, in particular on a reduced number of winter days on the location where the species is found in the wild, along with other obvious facts, had lead us to believe that there was a strong parity between air and water temperatures. It seams that the water never get so cool as expected and cold tolerance is not the most strong feature of this little fish. According to the information sources available, the water temperature may perhaps rarely fall below 16ºC ( 60.8ºF ) on the Bold Characodon habitat, in particular near the spring. This can be explained, particularly in such shallow pool, due to the influence of the spring, which provides generally warm flowing water and therefore doesn't allow it to suffer such expected direct influence from air temperatures.

This also explains why, at least in theory, Characodon audax could never survive outdoors to winter in Southern Portugal, particularly in regions with the same or even slightly higher mean annual temperature of their original habitat.

Reports on behavior regarding wild populations suggest a significant algae feeding, but the teeth of this species may indicate a more omnivorous diet including possible consumption of certain kinds of aquatic insects and other invertebrates. However, his relatively long intestines denote maybe more predominant consumption of plant matter than animal substances.

In captivity they show a clear tendency to a vegetarian diet but it changes a bit along different age stages. For this same reason it is desirable to take into account some vegetal food supplements, such as spinach and peas shelled after a slightly cooking, or other “ green “ alternatives to the usual food industry for the vegetarian species.

The optional supplements consisting of live ( or frozen ) animal prey, besides essential are greatly appreciated.

Apart from some initial reluctance to certain types of processed foods, the Bold Characodon is ideally suited to the broader proposals made in the fish keeping section. It will easily accept, in addition to a varied menu of vegetable options, brine shrimps, mosquito larvae, invertebrates aquatic and other natural foods or frozen fish or raw shellfish and ground as well as foods ( apart a component containing vegetable-based spirulina or other).

While they accept very well some domestic livestock and game meat, it must be avoided at all costs, since some of these components are relatively prone to cause health problems and diseases in the digestive tract, related with the ingestion of unsuitable animal food stuff.

If the feeding program meets the least parameters of a good diet criteria ( both in terms of quality and quantity ), the newborns are not harassed or wronged by adults.

There are, nevertheless, some reports of keepers who claim that in their tanks this species is fairly cannibalistic. This may be explained by unsuspicious neglected feeding requirements or other unknown factors. 

Only in some cases of adults misconduct like praying on newborn, or when demographic concerns with the maintenance of this species are exceptional, it is recommended that the expectant females should be placed in a well planted tank with a minimum water capacity of 15 to 20 liters, prior to giving birth.

In addition to a careful diet, pregnant females must have on such tank a superior water quality, in order to meet the physical and chemical parameters for the species with even more dedication than on the place where the rest of the group is maintained.

The recent mothers should spend another week or two in a separate recovery tank, accompanied merely by other females of their own species or some fingerlings, before being returned to their home community.

The offspring born on the maternity tanks described above, should be brought into the tank where the remaining elements of the species are kept, prior to sexual maturity, avoiding thus undesirable mating between siblings.

Sexual maturity is reached at about 4 months of age under normal conditions, although the females get pregnant after their brothers of the same litter sexual maturity.

Unlike Poeciliini, the Goodeid females do not possess the ability to preserve sperm, which means that after each birth they have to be fertilized again in order to enter in a new gestation.

The average offspring number per birth rounds between 8 and 20, but it can also be as low as only 2 or 3, in particular after the first pregnancy, and overcome 40 on extraordinarily large females kept under very favorable conditions. Ivan Dibble revealed a delivery of 63 offspring born from a female uniquely advantaged. 

The young are born relatively large in relation to the size of the mother ( between 7 and 10 mm ).

The gestation period usually lasts between 55 and 65 days, depending on temperature, water quality, food available and even on other less known factors.

In unfavorable conditions, pregnancy can be maintained for several months.

There are also reports of some keepers who say that elderly females of this species fail to reproduce, while continuing to live a normal life.

Newborns are not difficult at all to feed because, as noted before, they are born relatively large and very independent.

Sometimes their rudimentary umbilical cord, ( trophotenia ), could take nearly a week to be absorbed, but they become rather independent immediately after birth. In the presence of algae newborns begin to feed themselves within hours of birth.

Regardless of the varying abundance of algae to their own balanced diet one should feed them also with brine shrimp ( Artemia salina ) nauplii and Daphnia in convenient sizes, in addition to any industrial available dietary supplements for offspring.

V - Complementary notes

Taking in consideration the statement devoted to the Bold Characodon on the website “ Godeiden “ ( http://www.goodeiden.de/html/audax3.html ), all specimens of this species kept in Europe are descendants from only two couples, both resulting from the collection of Professor Robert Rush Miller. These ancestral pairs were brought by Ivan Dibble from the United States of America.

There are at least three species classified in the genus Characodon, one of which is considered extinct.

In addition to these three species, there are currently classification issues about two populations ( “ Abraham Gonzalez “ and “ Amado Nervo “ ).

The species Characodon audax and Characodon lateralis are morphologically very similar.

In addition to body coloration and even some other light variances, there are a number of differences, easy to identify positively in males from both species ( even under a superficial and less careful observation ).

Just as an illustrative example, and not considering other more obvious distinctions, we can see that the males of these species can easily show a obvious difference on the position of the anus in relation to the pelvic fins. In fact, on the Rainbow Goodeid the anal orifice is still in the belly area, covered by the pelvic fins when unruffled ( in all populations except for “ Nombre de Dios “ ), whereas in Characodn audax males it is located outside the covered area by the pelvic fins in resting position.

As regards to the extinct species, ( Characodon garmani ), only described through a single female specimen preserved since 1895, we can't look for such detail in particular.

Genetic analysis shows that the differentiation between the two existing species allow us to say that they are not the same, even though the degree of specification is still so close yet that allows fertile hybrids.

For the ability and easiness of this occurrence is strongly advised never to mix samples of both species in the same aquarium.

According to the English version of the website “ Godeiden “ - http://www.goodeiden.de/html/lateralis3.html, Dr. Dietmar Kunath, had obtained effortlessly hybrids of Characodon 1990, albeit unpremeditated.

As mentioned in the narrative of the author about this event, it is significant and must care should be taken in to consideration on the distinction between forced and induced breeding by human and cases of accidental occurrences or negligent care.

The successes achieved with this inopportune event becomes only roughly acceptable because the final result had allowed to obtain an empirical tool to investigate certain suspicious of taxonomic relationships between species, yet it is a practice not recommended because of the implications that it can represent in terms of biodiversity.

The problem arises with even more relevance in the face of the two species in question, since both are in serious risk of disappearing from nature.

Given their current situation in the wild, these fish are worthy of our best efforts to maintain them in captivity, especially since it is unlikely that one day they will be raise in a fish scale to be sold in stores.

Although there are references of keep this species in relatively small aquariums, the success of a group’s sustainability is based on the preservation of a large number of individuals as possible.

Even without some practice in maintaining this species soon you’ll be aware of the need for some room, although these are small fish.

The social behavior advises tanks up to 100 liters or more, even though we are not talking about the same consequences inherent in the conservation of territorial aggressive Cichlids. The dominant males usually do not kill their opponents as a result of fighting for territory or females, but the weaker individuals can die of starvation by not being allowed to come often to presence of the food.

At least initially, it is best to place them in a single species tank dedicated exclusively for this species, however there are an assorted group of other Splitfins, and even Poeciliids Cyprinids Characins that are compatible with their physical and chemical requirements and become excellent companions of community. The most common species of Corydoras are also useful tank mates, although they come from very different region of the world.

VI - Threats, protection and present status

Wild populations of Characodon are under dramatic decline since first describing by science.

One of the main causes can be associated to the fact that all the present small habitats are confined to arid or semi-arid regions, under strong pressure from human demographic expansion and agriculture activities.

Under the same circumstances one of this genus species is already vanish today.

Characodon garmani was only one of several relic fauna species from very confine places in Parras valley. Somewhere 1900 and 1953 they all have face extinction.

Together with this Goodeid the world lost other equally rare species from other represented families like the Stypodon signifer or the Cyprinodon latifasciatus.

Around mid XX century several springs dried out, contributing in a great deal to the disappearance of these fishes.

In another specific place, the remaining water body had been reprised. Inside the single remaining reservoir, anticipated to irrigate a cotton field, there was a culture of common carp ( Cyprinus carpio ).

Nowadays Parras Valley water bodies are subjugated by introduced species.

Only one or two of the original ones, most of all endemic species can still survive in isolated habitats.

Main rivers near Durango City like the Tunal are polluted by domestic waste waters and industrial sewage. Live on these areas is mostly represented barely by resistant lower life forms.

All fish endemisms are vanish.

In some very impressive places like at “ El Salto “ waterfalls, a black and smelling water is the result of local cellulose industry use of the river.

The decline of the Characodon genus species can also be related with the introduction of exotics by 1968. the most common introduced species were Cyprinus carpio, Carassius auratus, Lepomis marcrochirus e Micropterus salmoides.

Characodon genus fish decline and refuge in very remote areas can be due to environment destruction and severe alteration, deforestation, water contamination by domestic and industrial sewage, over exploration of water resources and certain human activities like agriculture.

Undoubtedly one of the most important, if not the most significant impact on these fishes decline in the wild was exotic species introduction. According to several information resources we can list the fallowing ones - Carassius auratus, Chirostoma spp, Cyprinus carpio, Gambusia senilis, Goodea atripinnis, Lepomis macrochirus, Micropterus salmoides, Oreochromis aureus and Oreochromis mossambicus.

Characodon lateralis is vulnerable according with the IUCN Red List of Threatned Species.

Memorandum about the Characodon genus : Regarding the 3 species placed on it, 1 is classified as extinct ( Characodon garmani ) ,  1 is classified as endangered ( Characodon lateralis ) and 1 is classified as vulnerable ( Characodon audax ).

For further knowledge or information about this please check Livebearer Cyprinodontiformes in the IUCN Red List of Threatened Species.

Other topics available about this species :

Sugested links :

Contreras Balderas, Salvador; 1975; Cambios de composición de especies en comunidades de peces en zonas semiáridas de Nuevo León; Contribuciones del Laboratorio de Vertebrados de la Universidad Autónoma de Nuevo León, Vol. 13, pp. 181-194.

Fitzsimons, John Michael; 1972; A Revision of Two Genera of Goodeid Fishes ( Cyprinodontiformes, Osteichthyes ) from the Mexican Plateau; Copeia, pp.728-756.
INEGI ( Instituto Nacional de Estadística, Geografía e Informática ); 2000; Censo Poblacional 2000, Mexico; http://www.inegi.gob.mx.

Smith, Michael Leonard and Miller, Robert Rush; 1986; Mexican Goodeid Fishes of the Genus Characodon, with description of a New Species; American Museum Novitates 2851 pp. 1-14, figs 1-4, table 1.

Smith, Michael Leonard and Miller, Robert Rush; 1986; Origin and Geography of the Fishes of Central México; The Zoogeography of North American Freshwater Fishes. John Wiley & Sons, New York. pp. 487-517;

Webb, Shane Anthony; 1998; A Phylogenetic Analysis of the Goodeidae ( Teleostei: Cyprinodontiformes ); PhD dissertation, University of Michigan, Ann Arbor.