Diving among the boulders I suddenly observed the green dashes crossing along me. I watched them among the rocks swimming against the strong current at great speed, I was surprised at how fast a cichlid could swim that way without an apparent big effort, from time to time an individual abruptly stopped and remained still for a few seconds looking around, then returning to it's race. The personality of the elongated cichlid I was watching was fantastic, and they didn't look like they were rushing because of my presence, which they seemed to ignore.
This event took place in April of 1990 just outside the Town of Santo Domingo de Ocampo (95 04'W.Lon.,17 09'N.Lat.) in the northern part of the isthmus of Tehuantepec in México. I was at Rio Dos caños, a small tributary of Rio San Juan belonging to the Papaloapan river system in the Mexican state of Veracruz and about forty five kilometers south from Catemaco crater lake, well known as the place of the witches.
The water (PH 8.0, GH 4, KH 5) was yellowish and warm over 28°C. The river at the place was an average of ten meters wide with perhaps twenty meters in the banks, despite of the fact that pools weren't plentiful because of the fairly great gradient of the river at the area, so a moderately rapid flow was the rule. Boulders could be found in the river bottom which was around one meter from the surface with deeper zones to two meters, pools had muddy to sandy bottom.
Indeed the cichlid I was observing was a Paraneetroplus species, the Rio Papaloapan equivalent specie of Paraneetroplus bulleri (Regan 1905) of Rio Coatzacoalcos. I thought it had to be the long looked after Paraneetroplus nebuliferum (Günther 1860), a fish people I know interested in central American cichlids had asked me for when they knew I had been collecting in the Isthmus before.
Paraneetroplus nebuliferum was first described by Günther in 1860 in page 318 of the publication of the London Zoological Society and first placed in the genus Chromis. That same year Günther re-classified it to the genus Heros in his Catalog IV, and 38 years later it was moved again by Jordan & Evermann, this time to the genus Cichlasoma, after that Reagn in 1905 created the genus Paraneetroplus for them and later considered as a section of the Cichlasoma genus. After many years it is Paraneetroplus is now recognized as a genus again, after the fall down of the Cichlasoma genus produced by Kullander in 1983.
The type locality of the fish was stated in the description as the eastern lowland streams of the Isthmus of Tehuantepec, more precisely at San Juan Evangelista. This last signaling makes it easy to find, San Juan Evangelista is a small town located in the Mexican state of Veracruz at the edge of Rio San Juan, the same river I was snorkeling and not far away.
I talked to a fisherman around Rio Dos caños and he told me the fish is commonly known as "Corrientera", a Spanish word referring to the cichlid habit to live in the currents, this same name is also applied to Paraneetroplus bulleri in it's natural habitat. The fisherman told me the cichlid was hard to get although he could catch several from time to time using a large nylon casting net with big mesh that do not close at the edges, which presents an inconvenience when casting in rocky areas. He confided me that in spite of the fact that the fish is not rich in meat, he like it because it is tasty an appreciated at the market place.
Fish coloration in normal mood is dominated by yellowish green hues on body flanks, head is of yellow coloration which intensify in the area below the eyes, bearing also purple hues in the gill plates near the branchial zone, there a black operculum similar to those found in the Thorichthys genus is present in the upper part of the gill plates. From the operculum above the base of the pectoral fins a black stripe crosses the entire flanks to the end of the long caudal peduncle just before where a black ocellus ringed in yellow is located in it's middle part bisected by the lateral line. Body coloration above this black stripe is yellowish olive green and below white with a light purple hue. Fins are translucent with just hues of red, blue and green, their tips rounded in all cases and the caudal being long and powerful as an adaptation to current swimming. Green scales are scattered alongside the black longitudinal band. Eyes of the fish are yellow with orange and purple markings.
The larger specimen I saw should have been a little bit over twenty centimeters. The green spots on lateral scales intensified in bright and number in larger males which also showed green spots on the forehead area.
At Rio dos caños I found Paraneetroplus nebuliferum living in the company of three other cichlid species, Thorichthys maculipinis called "Chonga" by the local fishermen was found abundantly in the banks and slower water flowing parts of the river, mainly over muddy or sandy bottoms, in lesser numbers Nandopsis salvini (Günther 1862) "Mojarra Pico de gallo" (Rooster peak cichlid) of beautiful coloration also shares quieter zones of the river, deeper zones are dominated by Paratheraps fenestratum (Güenter 1860), called by local people "Testa colorada", (Red head).
Paraneetroplus nebuliferum take advantage of the lush algae grown found over boulder stones, they would get close and rip off pieces of the vegetable. It's mouth structure facing downwards and the strength of the fish makes easy this task, in this regard the cichlid has no competition in feeding habits. Just Paratheraps fenestratum feeds also on algae to cover part of it's omnivorous diet but it seems to prefer doing this in slower flowing waters in the banks, where plenty of filamentous green algae grows in the shallows.
At the time of my visit during the ending part of the dry season, all cichlid species were found in breeding activity, Paraneetroplus nebuliferum pairs were seen in the rapids, mainly under the shadows provided by large trees located at the sides of the river, females would surround their fry numbering up to about two hundred in close circles while they grasped algae from the boulder rocks, males would keep their distance and surrounding the fry in circles too, keeping intruders at distance, once in a while both mates would stand together over the fry and would remain still in the strong current. I noticed that at the slightest sign of danger the fry would immediately scatter and get protection under the rocks, the female would retrieve at a safe distance, once danger passes the fry come out from their hiding place and get all together again following the signaling of the mother, who vigorously shake her fins to her fry.
Collecting some individuals proved quite a task, as this fish is very fast and intelligent. During a holiday afternoon when people of the town were taking a picnic at the river side and kids had been all day long swimming in the muddy pools, water was very murky and fish could not see the net's mesh, so a friend of mine and myself using casting nets were able to collect three adult specimens only after hundreds of net throwings, having to untangle the net from the boulders as often as once in three chances, with the net getting torn in the process. We however went out of light after a while and had to return to the place in the early morning of the next day. Water this time was clear about three meters visibility and "corrientera" very hard to catch with the casting nets. I decided to snorkel for fry with a hand net and this proved to be a very good choice, even in spite of the fact that small Paraneetroplus nebuliferum are not easy to get this way because of their fore-mentioned habit to scatter for protection below the rocks, and the difficulty of handling the net in the current, I could however get enough small individuals to take home, about forty of them.
For taking adult fish home we used large plastic jugs of fifty liters capacity, filled to one half and taking care that the water does not get warm, which is the worst danger in transporting fish alive due to oxygen depletion of the water with high temperatures. Fry was transported in a bucket with a lid and fed with algae. Water changes performed twice every day. An extra step we take is to add a chemical commercial tranquilizer to the containers of the large fish, preventing stress causing and oxygen consuming fights among them. Given this treatment cichlids have survive eight days long trips. This time all the "corrienteras" arrived home safely.
Once home I placed the P. nebuliferum in quarantine using a parasitic killing commercial solution, preventing with this the outburst and consequently aquarium spread of natural occurring diseases, which may hit the stressed newly arrived animals, quarantine I believe a must for wild caught fish. The "corrienteras" nevertheless got acclimated very quickly and started to eat voraciously since the day of their arrival.
I keep my P. nebuliferum in a well circulated and oxygenated tank with a warm temperature of 28°C and they seem to be doing just fine with healthy appetite, I of course pay much care to water quality because once I observed the natural conditions in which the fish live you know they will not settle for less.
I should remark the extraordinary personality of this fish, which do not get intimidated easily and has a fantastic appetite. In this regard I have not trouble to feed them. They would take willingly frozen shrimp, fish meat, lettuce, spinach, brine shrimp, as well as live aquatic insects I collect near home, I however lean over an herbivorous diet as in their habitat. It is hard to believe how much food this fish can consume.
As in the wild the fish keeps in constant movement in the aquarium, I provided them however with ceramic pots in the shape of caves that they happily use for cover and rest. Cichlid company however were not easy to find because Paraneetroplus nebuliferum proved to be quite aggressive towards any other cichlid I tried to house them with. So I decided to gave them their own two hundred liters tank which I divided with plastic light diffusers into three quarters, one for each individual.
Meanwhile fry were eating like their adult counterparts and growing quite fast, from about one to three centimeters in two months. They were being fed with live baby brine shrimp and softened spinach and soon started to show the adults aggressiveness among them, so I had to move them to a larger quarter.
After a couple of months I started to notice some kind of fondness between two of the adult Paraneetroplus nebuliferum I kept separated and decided to remove the divider under close supervision. Then the fish showed me at full the magnificence of their breeding dress hard to appreciate under the yellowish and dark water of their natural habitat.
Although the olivaceous tone of the fish flanks turns grayish, The middle three of the six black vertical bars the fish shows when dead and that are mentioned in the Paraneetroplus nebuliferum description become velvety black, this bars have the shape of a triangle with the broader side in the lower part of the flanks and the vertex at the height of the lateral line. Green spots in the mid-flanks scales intensify in color and look beautiful over the black background of the vertical bars, the black longitudinal stripe remains. Another feature is that the lower part of the head from the gills to the mouth and lips also turns velvety black.
Genital tubes were down the next morning and spawn took place over the gravel, near two hundred small yellowish translucent eggs about three millimeters long were deposited as the male fertilized them, during the length of the spawning for two hours fish kept swimming in circles around the spawning place. After a while however eggs were eaten by the pair, I then had to put the divider on again to prevent the pair to blame each other for their failure, a common occurrence with heroines as the male wants to spawn again while the female holds no more eggs.
Two weeks of heavy feeding had to pass until they were ready to spawn again. so I took the divider out and this time the pair choose the inside part of the ceramic pot for spawning, a behavior I found more in agreement of what it have to be in the wild, as they should spawn in nests among the rocks to prevent the water for washing the eggs away, this second spawn however didn't work one more time, as eggs were eaten by the next morning, so the divider had to be placed again.
Since then I haven't place the pair together but I will surely do it again soon, I trust this time they will settle for breeding or I will have to remove the eggs from parents care to assure me some fry.
New varieties of cichlids are being discover or re-discover year after year, central american cichlids are getting more popularity and many species like Paraneetroplus nebuliferum of great colors and personality will indeed make popular aquarium fish in the near future, after this, the biology and habits of the fish in the wild will start getting importance, and with the growing interest the widespread of now rare cichlids will surely become a reality, as it will soon be for Paraneetroplus nebuliferum.
© Copyright 1991 Juan Miguel Artigas Azas, all rights reserved
Artigas Azas, Juan Miguel. (mai 27, 1996). "The re-discovery of Paraneetroplus nebuliferum". Cichlid Room Companion. Consulté le février 25, 2021, de: https://cichlidae.com/article.php?id=2&lang=fr.