Liste des genres

Theraps

Theraps coeruleus
coeruleus

Theraps irregularis
irregularis

Theraps lentiginosus
lentiginosus

Theraps wesseli
wesseli

The Cichlid Room Companion

Sous-famille
Cichlinae

Tribu
Heroini

Genre
Theraps

Statut
valide


Rédacteur
Juan Miguel Artigas Azas

Publié
12-nov-2011

Dernière mise à jour le :
12-nov-2011

Femelle en coloration normale Theraps coeruleus femelle en coloration normale dans le Rio Tulija, bassin versant de l'Usumacinta [Mexique].Photo de Juan Miguel Artigas Azas. identifié par Juan Miguel Artigas Azas.

Theraps coeruleus Stawikowski & Werner, 1987

Versions
" A chameleon of color patterns with females taking the leading breeding efforts "
Couple de Theraps coeruleus dans la rivière Bascam, bassin versant du Tulija [Mexique]
Theraps coeruleus femelle gardant l'entrée de sa cavité de ponte dans un tronc d’arbre creux dans le Rio Tulija [Mexique]. Les mâles patrouillent sur le territoire des femelles au moment où elles changent leurs taches latérales normalement noires en blanc comme une indication de leur disposition à se reproduire. les femelles choisissent un mâle convenable et le courtisent en retour
Theraps coeruleus femelle avec des bébés dans la rivière Bascam, bassin versant du Tulija [Mexique]
Theraps coeruleus femelle en coloration normale dans l'aquarium de Don Danko [États-Unis]
Couple de Theraps coeruleus avec des bébés dans la rivière Bascam, bassin versant du Tulija [Mexique]

Décrit initialement sous Theraps coeruleus:

Historique de la taxinomie:

Groupements:

Étymologie: coeruleus = blue (Latin) (sometimes referred as caeruleus); in reference to the color of the females and also the breeding color of parental fish.

Types: Holotype: a 95 mm total length (TL), 77 mm standard length (SL) specimen collected by Rainer Stawikowski, Uwe Werner, Ingomar Kranz and Ernst Sosna on April 21, 1987 at type locality and preserved in the Department of Vertebrates (Ichthyology section) of the Zoological Research Museum Alexander Koenig (Zoologisches Forschungsmuseum Alexander König, Abteilung Wirbeltiere, Ichthyologie Bonn, Nordrhein-Westfalen) [Germany] with code ZFMK 15501. Paratypes: Four specimens collected together with holotype with a TL of 77, 81, 78 and 74.5 mm respectively (60.5, 66.6, 63 and 62 mm SL) stored at same locality as holotype with codes ZFMK 15502-05..

Diagnose: T. coeruleus differs form Theraps lentiginosus, its sister species, in several aspects, including a different snout shape, rounded in Theraps coeruleus and with a peak in Theraps lentiginosus. Theraps lentiginosus, particularly on males, have a scattered pattern of dots on flanks and on the unpaired fins with a higher density on the dorsal part of the flanks, absent or with much lesser density than in T. coeruleus. More significantly, males of T. coeruleus rarely reach a length of 15 cm, more often 12 cm in total length, while males of T. lentiginosus may commonly reach 25 cm in total length. Other differences include the fact that T. coeruleus lacks red markings in fins and body, common in T. lentiginosus.

Taille: Theraps coeruleus males reach 15 cm and females no more than 10 cm total length (Artigas Azas, 2009).

Dimorphisme sexuel: Males grow significantly larger than females, females have a blue area with two black blotches in the mid section the dorsal fin, missing on males.

Localité type: tributarie of Río Mizol Há at Francisco Madero, ca. 30 km south of Palenque, México.

Distribution: Theraps coeruleus is restricted to the middle zone of the Tulija river and its affluents in the Grijalva-Usumacinta river system in the state of Chiapas [México], around 100 meters over sea level. (from Artigas Azas, 2009).

Répartition par pays: Mexique (endemic).

Biotope: The habitat of Theraps coeruleus is characterized by wide (more than five meters) mountain rivers of clear cool water, in a temperature ranging approximately between 20 to 27°C. River beds are normally composed of boulders, rocks, gravel and sand, although some backwater areas of sunken leaf layers are also present. T. coeruleus chose the moderately fast flows as preferred foraging areas, normally away from the very strong currents and visiting the slower flow areas in smaller numbers or during breeding. Hardly ever are they found in stagnant water.

Water transparency is often well over ten meters, although normally rivers where T. coeruleus inhabit are less than three meters deep. Water is alkaline with pH measurements from 7.5-8.4, General Hardness ranges from 11-22° GD and KH from 7-28° (Stawikowski and Werner, 1998).

Localités: Bascam River (Mexique, native), Mizol-Ha River (Mexique, native), Rio Tulija (Mexique).

Alimentation: Theraps coeruleus feeds in the fast flowing areas or rivers with rocky and/or sandy beds, picking in the sand in rock pebble areas. Although I am not aware of stomach examinations, after having observed this fish underwater in multiple occasions it seems apparent that they feed on invertebrates encrusted in the rocks, hiding in the crevices or under them.

Individuals of all sizes group loosely together, swimming against the current while searching for edibles among the rocks. During feeding, they exhibit little or no aggression among themselves or to other fishes.

Unlike its sibling species T. lentiginosus, at least in my observations they do not seem to turn around pebbles in search for hiding invertebrates, although further observations may be necessary to corroborate this. (from Artigas Azas, 2009).

Reproduction: Breeding behavior in Theraps coeruleus is one of the most fascinating acts in Central American cichlids. The elaborate color changes involved with breeding phases are unique, as well as the fish mating system. The more colored females, with a beige base color and a strong blue in the lower head, chest and belly, are the first to take a step in colonizing the breeding area. They look for zones of slower water flow and search for a cave that will become their nest. Holes in sunken tree trunks, separated from the bottom, are by far the most desirable places, as it is apparent by the bigger more aggressive females holding every available hole. Second place come caves formed naturally by rocks, which sometimes have to be enlarged (in the adjacent substrate). In other occasions caves are dug up from below rocks in the sand on which they lay.

When females hold a territory they become territorial and express this mood with a row of six to eight big contrasting white blotches longitudinally on their flanks. The white blotches take the place of the normal black blotches that are seen in normal coloration. The normal coloration of the female then intensifies, being prominent two bigger black blotches ringed in blue on the middle part of the dorsal fin.

Males of all sizes, normally greenish-yellow in base coloration with eight to ten black blotches in a longitudinal arrangement on the middle part of their flanks, detect territorial females and parole by their territories. Females remain at the entrance of their caves and normally ignore passing males. Patrols can extend for hours. A chosen male, always bigger than the female, eventually is courted back and both potential mates circle each other in the territory. After the pair is established, coloration changes for both individuals and they start chasing all intruders away. At this point the specific name coeruleus become apparent, as both males and females develop a fantastic sky blue coloration all over body and fins, with just a black blotch visible on the middle of their flanks.

The spawning surface is cleaned by both fish for eggs to be placed and fertilized. About two hundred (depends on the size of the female) yellow ovoid eggs of approximately 2.1 mm length per 1.7 mm width (Coleman & Galvani, 1998) are attached to the ceiling or walls of the spawning cave, and fanned with the pectoral fins by the female. The female remains at the entrance or inside the spawning cave while the male patrols the immediately surrounding area. Eggs take about two days to hatch under aquarium conditions and four days later the little wrigglers, having consumed their heavy yolk sacs become free swimming and venture outside the cave.

At this point another coloration change takes place on the parents when a black pattern appears on the sky blue base color, with six incomplete bars going down from the top to the now black blotches found longitudinally on the middle part of their flanks, very contrasting on the light blue background. A black “U” is also formed just below the anterior base of the dorsal fin.

Parents herd their babies in the moderately fast flowing water. The babies forage on the surface of the rocks, presumably from small encrusted larvae, detritus and aufwuchs. When a perceived danger approaches, fry are quick to disappear below the surrounding rocks, and just the parents remain apparently guarding nothing. After the danger is perceived to have disappeared, the fry start popping one by one from their hiding.

As there are not studies in this regard it is hard to assess how long parents will guard for their babies, but juvenile fish of about two centimeters length are seen wandering among the rocks, where they efficiently take refuge in little crevices when danger approaches. When they reach about four centimeters length they are seen grouping with adults searching for food (from Artigas Azas, 2009).

Maintenance: Theraps coeruleus is a beautiful cichlid with a moderate aggressive disposition but it is by far not the easiest cichlid to be successfully kept and bred. This fish is shy, and if the conditions are not right this shyness get to extremes and apparently becomes stressful, and they don’t last very long. So this fish requires a good assemblage of dither fish for its well being, as well as proper lighting. A dark environment promotes shyness. Dither fish are ignored and just occasionally very small fish (livebearer fry) would be eaten. Caves and rocks are necessary in the aquarium. The minimum tank size I would personally recommend is 300 liters, although I have kept mine in a 1.5 m 400 liters aquarium, which seems to be perfect for this fish. Of course, I am sure some people would be successful in smaller tanks but you can’t expect to see natural a behavior there.

Derived from the natural conditions in which this fish inhabits it is easy to understand its requirement for very good water quality, as when water conditions go wrong, T. coeruleus is very prone to bacterial infections and eventual death. Of special consideration is the amount of dissolved oxygen and temperature. The fish suffer in the lack of the former and high value of the later, as can be easily seen in rapid respiration rates.

Water chemistry is better to keep it close to natural conditions, with pH above 7.0 and hardness above 5 GD. Water temperature is important, and either too cold or too hot water can easily damage the fish. Of special concern for its well being is not to keep them in too warm water, a range of 20-28 Celsius is accepted, where the middle range is preferred. Taking all this into consideration, coloration and behavior are optimal.

Feeding is not a problem, as they would greedily accept whatever offered to them. I tend not to offer too protein rich or fatty foods to my fish, to prevent digestion problems. Flake or frozen foods are accepted with no problem and the fish can be kept long terms on this regime without any apparent problem.

I believe that if the fish is kept in the proper conditions the main problem to solve in breeding them is to overcome its natural shyness. Proper water conditions, dither fish, good lightning, abundant food and companions that are not too aggressive are the key. More aggressive companions would stress Theraps coeruleus and prevent them from forming territories. If these conditions are met the fish would most likely breed. For a breeding cave, an inverted flower pot with an open base works very well in my experience.

Once pairs form and breeding procedures start, things will normally go well, although normally the first breeding attempts by the fish may result in failure. Fry accept brine shrimp as its first food and they normally prosper in the community aquarium, many of them even reaching adulthood there. Of course this happens if there are not efficient fry predators in the tank, and enough cover is provided.

Theraps coeruleus do better in a group of six or more individuals, and although they are not apparently aggressive, they actually are intraspecifically, although they rarely are fatally aggressive, especially if the space conditions are right.

Conservation: Theraps coeruleus n'est pas évalué par l'Union Internationale pour la Conservation de la Nature dans la Liste rouge des espèces menacées

Commentaires: Theraps coeruleus was placed in the genus Theraps Günther, 1862 (type species in Theraps irregulare) by its describers in the same sense that T. rheophilus had been placed in the genus Theraps by Staeck & Seegers (1985).

Theraps Günther, 1862, was redescribed by Robert Allgayer (1989) for elongated (2.5 to 3.32 times the depth in the standard length) rather compressed cichlids, with a long head (2.84 to 3.76 times in the standard length) and a terminal or subterminal mouth, a long caudal peduncle (0.9 to 1.48 its length in its height), scales ctenoid, among other traits. T. coeruleus is recognized by Allgayer as part of the genus Theraps and subsequently reaffirmed by Warren Burgess (2000). It should be noted however than in spite of the apparent relationship of T. coeruleus and T. lentiginosus with the type species of Theraps, T. irregulare, T. coeruleus and other species considered in Theraps because of it elongated shape (e.g. T. wesseli) could probably comply with the diagnosis more likely because a convergent evolution than because they share a monophyletic origin.

Although it has been suggested the possible synonymy of T. coeruleus with T. lentiginosus Miller (2005), who actually considered T. coeruleus synonym with Theraps rheophilus, I consider that Theraps coeruleus is a good species. Although Theraps lentiginosus has a large distribution range (specially compared with T. coeruleus) and exhibits a normal degree of geographical variability, T. coeruleus should be easily recognizable in every situation. The large size difference between them is also something to consider.

Tulija river, as part of the Grijalva-Usumacinta system, has a certain degree of isolation in the mountains of Chiapas, where other species have also been been recognized as divergent from their original forms (e.g. Thorichthys socolofi from T. helleri, Paraneetroplus omonti from P. gibbiceps, Priapella chamulae from P. compressa). All these species, inhabitants of clear mountain rivers, seem to be isolated from the rest of the Grijalva-Usumacinta drainage by the slower flow and different environmental conditions of the lowland Tulija river, and this seems to have been the case for quite some time. Time enough for allowing the striking differentiation of these endemic forms, which are certainly worth to recognize as unique.

Références:

Citation:

Artigas Azas, Juan Miguel. (novembre 12, 2011). "Theraps coeruleus Stawikowski & Werner, 1987". The Cichlid Room Companion. Consulté le mai 25, 2013, de: http://www.cichlidae.com/gallery/species.php?id=239&content=profile&lang=fr.


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