A breeding pair of Herichthys bartoni patrolling their fry through the water lillie beds in the Medialuna spring, Pánuco Basin, San Luis Potosí, S.L.P., México.
Back in 1890, Professor Alfredo Dugès from the Mexican University of Guanajuato visited the Rio Verde valley in the middle zone of the Mexican state of San Luis Potosi, found at about 1000 over sea level, his main interest being the biology of the area, special in many ways.
The Rio Verde valley is considered to be the place were a large prehistoric lake had existed, the lake, now extinct, left behind just the plains and the springs that used to feed it. Those springs had eroded the terrain to form the small lagoons now present. The very porous calcareous geology of the terrain provides the underground media necessary to drain the springs overflow, following paths and later popping up again to flow into the Verde river, and eventually down the highlands into the Pánuco system. Fauna and flora found in the Rioverde valley thrive in a special environment that has led them to specialization, and evolution of many distinctive species, many endemic to the valley.
Professor Duges, during his visit, among many other fishes collected a beautiful cichlid, and he knew he was dealing with a species then not knew to science, so he sent some preserved specimens to Dr. Tarleton Hofman Bean, those that would become the types of Acara bartoni, named after the ichthyologist Barton A Bean by when he published his description of the fish in "Procedures of U.S. Natural Museum" in 1892, with a type locality stated as Huasteca Potosina. This location a mistake probably originated by lack of complete information about collecting sites. The Rio Verde valley area from which Herichthys bartoni is endemic is not located in Huasteca Potosina, but in the middle zone of the state, A dry environment different in a striking manner to the Huasteca.
Even the fish was first placed in the genus Acara, it was later moved to the genus Cichlasoma by Jordan & Evermann in 1896, and then considered by the ichthyologist C. Tate Regan in his new sub-genus Parapetenia in 1905 (Regan, 1905), this sub-genus after a year was relegated to a section of Cichlasoma by the same Regan (Regan, 1906). In this genus the fish remained until the big Cichlasoma mess started in 1983, once the Swiss ichthyologist Sven Kullander restricted the genus to some South American representatives closely related to the genus type specimen, Cichlasoma bimaculatum (Kullander, 1983).
From that point the generic status of bartoni, as well as that of around a hundred of other Central American cichlid species, placed before in 'Cichlasoma' was left in the air. So, now just further study on this matter will eventually bring bartoni relationship with the existing and future genus that will replace Cichlasoma.
Medialuna spring, Pánuco system; Rioverde, San Luis Potosí, México.
The distribution of Herichthys bartoni is restricted to the springs of the Rio Verde Valley, located west from the city of Rio Verde (N.lat. 21°51'52", W.lon 100°51'41") in the Mexican State of San Luis Potosi, to the town of Villa Juarez, fifty kilometers to the northwest, and to the mountains at the edge of the valley, twenty kilometers south and west from the city. It is found in the small lagoons eroded in the calcareous valley floor by springs, and although it is sometimes considered as endemic from "Medialuna" Lagoon (Half moon), this is not the case. The fish inhabits other springs in the area, some of the bigger being "Los anteojitos" (Small sun glasses), "Manga larga" (longs sleeve), "Los peroles" (the pears), "Las tablas" (the tables), "Laguna de San Bartolo" and "El aguaje" (the water spring), but it is also found in some smaller ones, as well as in the artificial irrigation channels or the small natural creeks "Acequias" that flow from some of the springs some tracks exposed and some underground, but none of this interconnecting.
An artificial channel that flows from the largest and more famous of the springs, "La Medialuna", first dug more than a century ago but paved and extended in the seventies, now cross underground the Verde river and has been the path for Herichthys bartoni to reach the upper perennial parts of this water course, although in this river it is just found in very small numbers, perhaps due to difficulty to establish in the very different riverine environment.
'Cichlasoma' bartoni adult male in normal coloration (One of the many phases) swimming in the Medialuna spring, Pánuco; San Luis Potosí, México.Photo by Juan Miguel Artigas Azas.
Springs of the Rio Verde valley are small bodies of water, the largest, La Medialuna, whose main lagoon have the shape of a half moon with a maximum diameter no more than one hundred meters, but a depth of thirty six (118 feet). "Los anteojitos" however, is formed by two small lagoons that interconnect by a small channel five meters long, where the largest of the two lagoons is no more than forty meters in diameter. "El aguaje" is a small spring and Acequia that after a small exposed course disappears underground, it forms in its course small marshes where bartoni is found in a plentiful way.
Water conditions in the springs vary, in "La Medialuna", "Los Anteojitos", "Los Peroles", "Las tablas", "Laguna de San Bartolo" and "Manga Larga" are very close. Water in those springs is warm 27-32° Celsius and extremely clear with visibility of more that thirty meters in the clearest undisturbed days (But in La tablas where there is less visibility). Water chemistry measurements show a pH in the alkaline side around 7.8 to 8.0 and a general hardness of more that 100° German, Carbonate readings are normally no more that 15°.
Aquatic vegetation in the lagoons comprise mostly extensive beds of water lilies (ninphaea) that form in the shallower areas where bartoni is found, the springs floor is formed by a thick layer of detritus easily disturbed by swimmers or bad weather, causing clear water to become murky, a common event during weekends in Medialuna spring where scuba diving schools practice all around the year but in the coolest days. Rocks and driftwood are normally absent in the springs and Acequias (But in Los Peroles). Shade is provided along the edges of the springs and Acequias by the overhanging vegetation. And although natural tress are almost absent in the valley, there has been some areas planted by the county government around some of the springs for the purpose of provide shade to the visitors.
Water flows are normally very slow but in some of the irrigation channels it becomes rather fast, this however has no cause any limitation to Herichthys bartoni, that is found everywhere up to a profundity of about five meters in the deeper lagoons.
Environment in the Acequia "El aguaje", four kilometers south of the town of Villa Juarez in the most northern part of the bartoni range is quite different, there water temperature can fall to lower 20° Celsius or perhaps less in the winter, and it is about 25°C in the late dry season, visibility is no more that two meters and aquatic vegetation and weeds are found profusely in addition to ninphaea sp. in a very muddy floor.
Herichthys bartoni lives in the company of several other species, cichlids are found in the form of Cichlasoma labridens, "The yellow labridens", found in the entire range but in much smaller numbers than Bartoni, this labridens form is also endemic, although a similar morph is found in the Verde and Santa Maria rivers. Livebearers are found in the form of the endemic goodie Ataeniobious toweri, Cyprinodonts are represented in most of the springs by the endemic Cualac tesselatus, Cyprinids found are Dionda dichroma and Dionda mandibularis, Characinids are represented by Axtyanax fasciatus and the Ictaluridae family by Ictalurus mexicanus.
Introduced species are also found in the range, mainly Oreochromis aureus who has been blamed to be a potential threat to the Herichthys bartoni populations and has led to include this fish in the 1990 endangered species list of the International Union for the Conservation of Nature. Oreochromis aureus was both introduced in the springs and Verde river and farmed in artificial ponds fed by Acequias near Villa Juarez. Farming did not turned out to be profitable and was abandoned. Introduced populations have different ends. In "Los anteojitos" spring is now vanished for natural causes, in "La Medialuna" they have been luckily decreasing in number and those found normally present assorted diseases, normally exophtalmia. In Villa Juarez and the Rio Verde however the history is another, there the Tilapias are plentiful and thriving but so far do not seem to pose any danger to the Cichlid species.
Other exotics before just limited to Rio verde include Herichthys carpintis (perhaps introduced from the lower Pánuco (Miller, per. comm.)), Gambusia panuco and Poecilia mexicana, those have invaded the Medialuna main irrigation channel about fifteen years ago and in the last years have established in the Medialuna itself. Herichthys carpintis doesn't seem to be thriving well at least in Medialuna spring but in the first years of colonization it hybridized with Cichlasoma labridens, although lately I have not seen any more hybridization. The impact on Herichthys bartoni Medialuna population it is not known but so far it doesn't look to put a big stress on them, although the very short food supply in the springs lead small carpintis to prey on natural cichlids fry, both bartoni and labridens.
Another introduced species in "Medialuna" spring is Poecilia latipunctata from Rio Tamesí, the northern arm of Rio Pánuco, threatened in its natural range but thriving in the spring, but seems not to be a problem for the subject of this writing.
|A pair of 'Cichlasoma' bartoni taking care of fee swimming fry, Medialuna spring, P´nuco; Rioverde, San Luis Potosí, México.Photo by Juan Miguel Artigas Azas.|
|Pair 'Cichlasoma' bartoni taking care of spawn, inside the cave. Media luna spring, Pánuco; San Luis Potosí, México Photo by Juan Miguel Artigas Azas.|
Herichthys bartoni is a robust cichlid, males growing to a total length of about 18 centimeters but females just reaching a maximum total length of about 11. Body is rather. Head profile is curved in the frontal zone with a small hump in adult males and a straight line from there to the upper lip in some individuals while some others show a strong convexity over the eye. Snout is long and pointed with the jaws equal or the lower projecting a little bit. Lips are thick with anterior teeth that form canines and a distinctive frenum found in the lower one. Pelvic fins are short not extending to the base of the caudal fin. Soft rays of the dorsal and anal fins not produced showing a rounded shape that do not extend far from the base of the caudal fin. A rather long caudal peduncle longer or equal to its depth holds a sub truncate tail.
Herichthys bartoni is easily distinguished from the yellow labridens by the absence of a purple scaleless blotch just behind the base of the pectoral fin, a distinctive feature of the labridens species complex including both steindachneri and pantostictum.
Base coloration is gray to light brown in most individuals with some few showing a strong yellow coloration with a red area just behind the base of the pectoral fins. An horizontal line of black blotches goes from just behind the eye to the base of the caudal fin, where a big black blotch is present, some scales in the lower half of the body show a light blue spot on them.
Breeding coloration is simple and striking, and perhaps one of the most beautiful seen in Central American cichlids, the upper half of the body in both sexes turns white while the lower half turns velvety black, that includes the fins. This coloration last from spawning to the end of the fry caring period, and it is sometimes also seen in courting individuals. Herichthys bartoni, when small, stays close to the vegetated areas at the edges of the lagoons and channels, taking good advantage of the limited food supply around. They eat the algae on the back sides of water lilies leaves. Larger juveniles also often congregate around feeding sympatrical yellow labridens. The labridens, black in coloration when feeding, introduces its belly into the soft substrate proceeding to wag it searching for snails, the smaller or unwanted of those left to congener juveniles, but other inverts take by bartoni as well.
Bartoni eats opportunistically but it seems to do this just when food is scarce, its favorite diet is no doubt small algae, and this is easily certified by the large number of individuals always found grazing the concrete locks built in the channels to control water flow, an artificial hard surface that provide proper attachment and sun exposure to the algae grown.
Herichthys bartoni is a monogamous biparental cichlid. Due to the very stable water conditions of the springs and in contrast to most Central American cichlid species, breeding pairs are found all around the year, but with a peak in the dry season. They start breeding when small, paired females as small as six centimeters are a common sight. Males prefer to wait a little longer, the smaller I have seen perhaps being ten centimeters in size. Males are always larger than their consorts, and extreme cases of males 18 centimeters with females six or seven is not an uncommon event, although normally males two or three centimeters larger than the females are the rule. Pair courting seems to take some time as they are commonly seen wandering in pairs along the channels shaking their bodies from time to time and grazing together on a water lilly sumerged leave. At this point the normally light coloration darkens but without present yet the striking black and white characteristic pattern.
Pairs spawns in caves at the stepped sides of the lagoons or channels, or beside a rock, most of the time they try to find a natural cave or one previously dug, that they clean and enlarge, if this is not possible they dig theirs in the calcareous walls. Caves are narrow and long, and sometimes present more than one entrance. The diameter of a common cave is just enough to let the male enter or a little bit wider, five centimeters is perhaps the common rule, they are however no less than twenty centimeters long with a enlarged chamber at the end. There the female sticks the yellowish rather large eggs to the upper wall, numbering in the couple of hundreds. In this respect they do not show the huge number of eggs deposited by other Central American large Cichlids.
Under aquarium conditions the eggs take two and a half days to hatch at 29°C and the wrigglers are able to swim after they consume they yolk sac five days latter. While they are being taken care, the female stays most of the time inside the cave and the male at the close surrounding of the entrance defending a territory no more than one meter in diameter, the female comes out once in a while and disappears from the territory, perhaps looking for a quick snack. Nevertheless, after a short time she comes back and after flickering her body side to side to the male's she then returns to her position inside the cave. At the sight of danger, the male, instead of fleeing away as normally would happen with most Central American cichlids, he gets inside of the cave and stays at the entrance until threat disappears.
Some hours after the fry are free swimming they are taken out of the cave by the mother, at this point they start looking for food under the close supervision of the parents always leading them at a close distance by the quick spasmodic closing and opening of the male's fins, while the female stays just above. At this point the fry graze on the water lilies leaves or on the soft detritus. They will never come back to the cave and just in the late afternoons or at the approaching of any potential danger they will be hidden by the pair under the water lilies leaves closer to the floor.
The main potential danger to the fry are the tetra Axtyanax fasciatus, that gregariously may take a fry from the close pair care from time to time, Herichthys carpintis young trying to colonize Medialuna also will prey on the little bartoni when they are able to, and perhaps in this respect they are more efficient that the tetras themselves. Fry will be taken care of by the pair until they reach a size of about one centimeter, when they will start to abandon their parents to seek for shelter in the dense overhanging vegetation of the springs edges.
The main pedrators of Herichthys bartoni in the natural habitat are found in the shape of plentiful water turtles, an aquatic specie being endemic of the area. Large water snakes of more than two meters length are also a common pedrator of the fish. Fish eating birds are also found in good numbers but they seem to be more interested is Axtyanax fasciatus than in Cichlids. People around do not like Herichthys bartoni for food, in this respect they prefer the introduced Oreochromis aureus that is mainly caught in the main irrigation channel.
In my experience with captive Herichthys bartoni it is an extremely territorial fish, showing a very aggressive actitude towards conspecifics that may also extend sometimes to fishes of different species, not restrictive to Cichlids. But this event is more likely to happen in smaller than 200 liters tanks.
Regarding feeding this fish puts no limitation to it's diet, being a heavy eater of whatever edible you have to offer to them, but small fishes being normally ignored (At least by the common bartoni form). Although the fish eats too much it's growing rate in my experience is slow, and it takes several years for a male before he reaches their maximum 18 centimeters in total length.
The fish adapt to whatever water chemistry you provide them and will breed in it but prefer warm water over 25°C in temperature. In large tanks Herichthys bartoni normally will not establish territories outside breeding time and may be seen looking curiously for food in any possible place, mainly close to the bottom of the tank. In the afternoon or when resting the fish will look for shelter where offered and once hidden just his head will peak.
Dominant or breeding fish will develop the beautiful contrasting white and black pattern and breeding will take place in any hidden area; among rocks, inside a flower pot, or perhaps in the vertical surface behind a rock. After hatching occurs wrigglers are placed in a pre dug pit in the tank's substrate and once free swimming they will be guided through the tank. At this point the fry can be easily feed with artemia nauplii that they will gladly accept until they are large enough to take some other freeze, prepared or dry food.
Herichthys bartoni taken from the wild habitat should be careful quarantined, otherwise a common disease of the area could show up and quickly get established in the tank. This disease presents in the form of a bloating area in one of the flanks that pops scales out to the flesh and continuously circularly enlarge until it kills the fish. This disease just attacks Cichlids but it may become a headache to eradicate. I have had luck treating the infected fish with Clout® for five days but it will leave an ugly scar on the fish flank and once established it will outbreak in some other Cichlid after a while.
With this I have wanted to give you an insight on the biology of this beautiful fish that together with other restricted fauna habits the delicate ecological niche of the Rio Verde valley in San Luis Potosí, an environment very prone to disruption that must be protected by ourselves and that in return it will offer us with one of the most beautiful places in México to observe and enjoy the behavior of aquatic fauna. An event that will doubtlessly lead us to appreciate and love its uniqueness.