The Papaloapan river or Rio de las Mariposas (river of the butterflies) flows down to the east from the volcanic highlands of the Mexican plateau, originating from cold water springs in these mountains. At first a rapid mountain stream, further downstream the river becomes wider and flows peacefully across a landscape characterized by tropical lowland vegetation, eventually emptying into the Gulf of México at the city of Alvarado, between extremely beautiful salt lagoons. The drainage of the Papaloapan and its smaller tributaries is bordered to the north by a volcano belt 60 kilometres north of Veracruz, the state capital. This belt is the remains of a large volcanic chain which once extended from the central part of the country to the Gulf of México, and meets the sea at Punta del Morro, just south of the 20th parallel north. This mountain chain acts as an effective geographical barrier to the spread of the freshwater fishes.
The taxonomic background of
In 1904 Seth Eugene Meek recognized a fish inhabitant of this basin as a new species which also justified the erection of a new cichlid genus, Thorichthys. The diagnosis of this new genus reads: "Body deep, much compressed; mouth rather small; caudal fin lunate, its outer rays produced into a filament; pectoral fin long and pointed, about as long or longer than head; subopercle with a black blotch, otherwise as in Cichlasoma". Additional traits were also mentioned, including a small size of no longer than 6 inches (about 15 cm), the absence of a nuchal hump, and a large variability between populations.
The meaning of the word Thorichthys is defined by Meek (from Greek) as a leaping fish. Meek's account on the matter goes as follows: "These little fish (i.e. Cichlasoma helleri) are exceedingly numerous in small isolated ponds, especially where there is a considerable amount of vegetation. They are attracted by anything which enters the water and will jump out of it in an apparently playful mood. When abundant they are easily caught, for as soon as your finger touches the water, they will come leaping towards you". However, I must confess in many occasions I have been around this fish I have never see them leaping. Meek's account must have had more to do with hungry isolated fish, probably in a small pool after the rainy season, than with a joyful attitude on the fish part. Our days possibility of observing such a behavior is however very much reduced, as such jumping fish will quickly end up in a fish soup somewhere.
Species listed by Meek as suitable for inclusion in his new genus were Cichlasoma aureum (Günther), C. affine (Günther), C. friedrichsthalii (Heckel), C. rostratum (Gill & Bransford) and C. longimanum (Günther). Officially Meek recognized however only two species: Thorichthys helleri (Steindachner) and the new Thorichthys ellioti, named after Professor D.G. Elliot, curator of the Zoology Department, Field Columbian Museum.
Thorichthys ellioti was described from material collected at Motzorongo, Veracruz (Lat.18°15' N., Long 96°43' W.), stored in the Field Columbian Museum (Field Columbian Museum, 4727). The publication also includes a drawing. Motzorongo, the type locality, is located on the Tonto river, one of the main affluents of the Papaloapan river system. Over the years extensive collections of this species have been carried out, which remain stored in museum collections around the world.
The genus Thorichthys was later designated a section of the genus Cichlasoma by Regan in 1905. Regan recognized three species in this section: C. aureum (Günther, 1862), C. affine (Günther,1862), and C. callolepis. (Regan, 1904). Thorichthys ellioti was considered a junior synonym of Cichlasoma (Thorichthys) aureum, together with C. (Thorichthys) helleri (the second Thorichthys recognized by Meek) and Heros maculipinnis, a species described by Franz Steindachner in 1864. Later, in 1907, Meek considered Thorichthys a subgenus of Cichlasoma.
C. ellioti and C. helleri were again considered distinct species by Newton Miller (1907) and by Carl L. Hubbs (1936), an opinion which was later followed by Robert Rush Miller (1961), who also gave additional characters for differentiating the then Cichlasoma (Thorichthys) group. Kullander (1983), in restricting the genus Cichlasoma to its South American representatives, left most Central American species without any formal generic placement, but regarded Thorichthys as a group "that should be recognised as a separate genus". Robert Rush Miller (in a recent posting (1996) on the Internet: Cichlid-L: the cichlid systematic and distribution Internet list) considers Thorichthys a valid, monophyletic genus with nine representatives (one yet to be described).
The neglected description
In 1864 Steindachner wrote a paper describing several now well-known Central American cichlids: Heros lentiginosus, H. helleri, H. bifasciatus, H. gibbiceps, and H. maculipinnis. The last of these matches in all taxonomic aspects the description of Thorichthys ellioti by Meek. Moreover the type locality of T. maculipinnis is given as Rio Jamapa, which belongs to the Papaloapan river system, and from which T. ellioti was also described. The type localities of T. ellioti and of T. maculipinnis are not far from one another. Besides this taxonomic information, a personal knowledge of the area and the fish fauna leads me to conclude that we are talking here about the same fish: thus T. ellioti is probably a junior synonym of T. maculipinnis. The Rio Jamapa, although in the drainage area of the Papaloapan, is not a direct affluent of the large river but empties direct into the Gulf of México. This fact may possibly suggest the recognition of T. ellioti as a distinct species but, knowing the cichlids of the entire Papaloapan system, I feel this is highly unlikely. Meek (1904), when describing Thorichthys ellioti, didn't recognize Heros maculipinnis as a member of his genus Thorichthys; this was rectified later by Regan (1905), who included it in his Thorichthys section. It is not hard to imagine why this happened. It seems that the specimen described by Steindachner as Heros ntaculipinnis has badly damaged fins and thus lacks some of the diagnostic characters recognized by Meek for Thorichthys. If both descriptions are proved to refer to the same species, as I think likely, the name maculipinnis will have precedence over ellioti, which will then become a junior synonym of it.
Thorichthys maculipinnis inhabits the entire lowlands of the Papaloapan system below an altitude of 300 metres. All rivers with an average water temperature above 24°C are home to this beautiful fish, including large, wide rivers such as the Papaloapan itself as well as very small affluent creeks no more than a metre wide and 10 cm deep. As mentioned by Meek, variation in colour pattern and morphological characters is apparent in different geographical areas. Individuals inhabiting the Rio San Juan Evangelista and its tributaries (the eastern arm of the Papaloapan), exhibit an intense and distinctive yellow coloration on the ventral area, which, together with the otherwise orange coloration of the fish, makes it look especially beautiful. Fishes from the central part of the system, including those from the Tonto and Papaloapan, have an enhanced blue coloration on the scales along the sides (eg in the Rio Obispo), as well as a stepped head and a longer snout. Specimens from the western part - Rio Blanco and separate rivers such as the Jamapa - instead exhibit more and brighter bluish-green dots on the cheeks and lower part of the flanks.
The area in which Thorichthys maculipinnis occurs extends from the Gulf of México in the east to the Mexican plateau in the west, and from the volcanic mountain chain running west-east to Punta del Morro on the coast in the north to the watershed of the Coatzacoalcos river system in the south (where it is not found).
The habitat is characterized by clear, not very clear or decidedly murky water, sometimes with zero visibility, in slow-flowing rivers and lagoons, which mostly have sandy bottoms and lots of cover in the form of driftwood. Because of the often murky water, light penetration is minimal and aquatic plants are not present in most of the range; overhanging vegetation is, however, common. The banks and river bottoms are normally covered with a layer of tree leaves. The rivers are commonly surrounded by tall forest trees whose roots normally extend into the water, providing additional cover for the Thorichthys. The chemistry of the water includes a pH between 7.5 and 8.0 or more and a hardness of about 8 DH. The temperature normally ranges between 25° and 28° C.
Fishes of many families live together with Thorichthys, sharing the rich habitat. The cichlid family is represented by Petenia splendida, "C" urophthalmus, Archocentrus octofasciatus, "C" salvini, Paratheraps fenestratus, and Paraneetroplus nebuliferus. Many other fishes are present, most commonly including members of the families Atherinidae, Belonidae, Characidae, Clupeidae, Centropomidae, Cyprinodontidae, Eleotridae, Gerreidae, Lepisosteidae, Mugilidae, Pimelodidae, Poeciliidae and Symbranchidae.
After many hours of underwater observation in clear water rivers, I can say that the main character of T. maculipinnis is that of a gregarious cichlid. Groups of adults and juveniles wander through the habitat, always in close contact with the bottom and looking at it. They stop from time to time and pick up small animals located in the substrate, using their long snouts to poke into the sediment. The mouthful is chewed and inedible material expelled via the gills. They don't seem to possess a strong pharyngeal mill, so prey needs to be soft - snails are probably not taken. It is not particularly surprising that specimens from the middle part of the Papaloapan river system have a more pronounced snout, given that they normally live over muddy, instead of sandy, bottoms, and thus seemingly need to penetrate deeper into the substrate to capture their prey. A similar adaptation can be seen in some species of the Herichthys labridens group in the Pánuco system. Those H. labridens and H. pantostictus which forage over soft bottoms have a more pronounced snout than their counterparts living in rivers with sandy substrates.
Breeding takes place mostly from February to May, when males pick small territories (no more than 50 cm in diameter), normally in the slow flowing shallow water under or close to the cover of overhanging vegetation or driftwood. They defend these territories, which usually have a small rock at the centre, and court passing females by extending their fins, opening their gill covers, and assuming a 45° "headstand" position. Many females respond to this courtship, approaching the male, circling with him a couple of times and assuming the same head-down position, and then leave. Later one female returns, and thereafter stays with the male. Thorichthys normally form colonies of several adjacent pairs. Some Thorichthys species seem to favour leaves as spawning sites, but this is not generally the case in T. maculipinnis, although sometimes it does. Interactions between neighboring pairs are commonly seen and provide a very interesting spectacle. They assume a threatening pose, facing each other with the gills open, making small, ritualized, runs forwards and backwards, sometimes accompanied by sudden outbursts of aggression during which the fishes simultaneously lock mouths, although no damage is ever done. The black blotches on the gill covers of Thorichthys species, a characteristic of the genus (but absent in one representative, T. callolepis)), enable them to appear much larger than they really are: the distended gills and gular pouches, together with the black blotches, give them the appearance of a large fish when seen from the front.
Spawning normally takes place early in the morning and the eggs are placed in tight-packed concentric circles on the chosen small rock or pebble. No more than two or three hundred small eggs will be laid, and these are defended aggressively by both male and female, no matter what the size of the threat. When the eggs hatch (two days under aquarium conditions at 28°C) the wrigglers are placed in a small pre-dug pit, normally located at the base of the spawning site. The fry take several days (five under aquarium conditions) to consume their heavy yolk sacs before they start swimming. Free-swimming fry stay in tight packs, closely guarded by their parents. It is important to note that unlike some other cichlids, members of the genus Thorichthys form pairs that always stay close together looking after their progeny, and facing any threat. The male leads the family in circles around the breeding area, never going far from the original spawning site. During such "strolls" the fry keep constantly together beneath the female, picking at small organisms found on the bottom. During the night the fry huddle beneath both parents, who normally choose a small depression in which to rest. Fry protection and leading lasts until the fry feel secure enough to venture around the habitat on their own, usually when they have reached between one and two centimetres total length. Large groups of juveniles are normally found picking in the substrate close to the banks in very shallow water and among the vegetation fringing the stream. They stay there until they are large enough to join the adults in deeper water.
At the point when the fry abandon their parents' protection, the pair splits up and male and female go their own way. As is the case with other Thorichthys species, sudden non-expected rains during the breeding season may completely sweep away a pair's effort, resulting in their having to start the breeding process all over again.
Some guidelines for aquarium maintenance
Thorichthys maculipinnis can be kept and bred successfully under aquarium conditions. Good water quality is a must for ensuring healthy fishes, which otherwise easily succumb to internal and external bacterial infections. The pH and the hardness of the water are not critical, as long as the water parameters do not differ highly from those found in their natural habitat, water should be free of ammonia and nitrite. Water temperaturure should be a special concern, T. maculipinnis is found in water that ranges from 22 to 28°C, and they seem to suffer when kept outside this range.
Although T. maculipinnis can be kept and bred in aquaria as small as 80 litres, I would definitely not advise quarters smaller than 300 litres. In large aquaria one can observe reasonably natural behaviour which is mostly absent in smaller tanks. I usually provide my cichlids with a sandy bottom in which they can pick. Driftwood and cover should also be provided, as well as some sort of "dither fish" to help them overcome their shyness. Large cichlid companions should be avoided in normal-sized aquaria (eg 300 litres), although in very large tanks they shouldn't be a problem.
Special care must be taken when feeding Thorichthys. Although they greedily accept any fare, fatty products, eg beef heart or poultry, must be avoided, as they can cause digestive problems. Pairs with fry can be kept in a community tank without much problem. Fry can take Artemia nauplii as a first food, and one should take special care to keep the fry well fed, otherwise they will develop permanent deformities during growth.
I am glad to be able to report that, in spite of deforestation and heavy pollution of many of the rivers in which Thorichthys maculipinnis is (or was) found, the existence of this little gem is not directly threatened although this may change in the near future. Hopefully the massive habitat destruction taking place in México will soon be halted and reversed, before all its fishes are in danger of extinction.
- Hubbs, C. L.; (1936); Fishes of the Yucatan peninsula.Carnegie Inst. Washington, 457:157-287, pls. 1-15.
- Kullander, S.O.; (1983); A revision of the South American cichlid genus Cichlasoma (Teleostei: Cichlidae), Swedish Mus. Nat. Hist., Stockholm.
- Kullander, S.O.; (1986); Cichlid fishes of the Amazon river drainage in Peru. Swedish Mus. Nat. Hist., Stockholm.
- Meek, S. E.; (1904); The freshwater fishes of México north of the isthmus of Tehuantepec. Field Columbian Museum, Vol. V: 1-252.
- Meek, S. E.; (1907); Synopsis of the fishes of the great lakes of Nicaragua. Field Columbian Museum, Publ. 121, Zool. services, 7 (4): 97132.
- Miller, N.; (1907); The fishes of the Motagua river, Guatemala. Bull. Amer. Mus. Nat. Hist.1984(4): 933-940.
- Miller, R. R. & C.N. BERNARD; (1961); Variations, life colors and ecology of Cichlasoma callolepis, a cichlid fish from southern México, with a discussion of the Thorichthys species group. Occ. pap. Mus. Zool. Univ. Michigan, Nr. 622.
- Miller, R. R. & J. N. Taylor ;(1984); Cichlasoma socolofi, a new species of cichlid fish of the Thorichthys group from Northern Chiapas, México. Copeia 1984(4): 933-940.
- Regan, C. T. (1905); A revision of the fishes of the American cichlid genus Cichlosoma and of the allied genera. Ann. Mag. Nat. Hist. Ser. 7(16): 60-77, 225-243, 432-445.
- Regan, C. T. (1906-1908); Pisces. Biologia Centrali Americani.
- Steindachner, F. (1864); Beitrage zur Kenntniss der Chromiden Mejico's and Central-Amerika's. Denkschr. Akad. Wiss. Wien., 23(2): 57-74, pl. 1-5.
- Other sources: CICHLID-L, The cichlid systematic and distribution Internet list, maintained by Sven Kullander at the Swedish Museum of Natural History. To subscribe send an e-mail to [email protected] with the following message contained in the text "Subscribe CICHLID-L (Your name)". (leave out the quotation marks and parentheses).
© Copyright 1996 Juan Miguel Artigas Azas, all rights reserved
Artigas Azas, Juan Miguel. (août 17, 2000). "The forgotten Thorichthys maculipinnis". Cichlid Room Companion. Consulté le mars 05, 2021, de: https://cichlidae.com/article.php?id=143&lang=fr.