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Rare Jewels of the Tehuantepec Isthmus
|A cura di Juan Miguel Artigas Azas, 1991.|
(This article was originally published in Cichlasoma power, Bulletin of the Cichlasoma study group; 1991; Vol. 11 No. 3. And in Buntbarshe Bulletin, Bulletin of the American Cichlid Association; 1993; Numbers 154/155; pp. 14-22/2-6.).
Collecting cichlid fishes has always being my passion, the feeling of getting a fish you have never seen before is a source of a great emotion and to put on a mask and snorkel and swim among their world watching their behavior made me forget of anything else in the world, it's just an endearment of nature beauty to a beholder.
This is what take me collecting at least twice every year, it doesn't matter at all if I seen the fish one or a hundred times, it is just the feeling of being there spying their world and for a moment feeling part of it.
This year I made a collecting trip in May, I did it in the company of a good friend of mine, Don Danko from the United States, now after several years is getting an habit going collecting together one or twice each, and this time we decided the Tehuantepec Isthmus.
It was not our first time there, we had been in the isthmus collecting two years ago, but we wanted to come back to try again with some hard to find or hard to collect cichlids, as well as to try luck with some species described from the area but not so far found by cichlid fanciers. We were also very curious to get to the Catemaco crater lake in the Northern part of the Tehuantepec isthmus and find out what is all about with this so called "pink fenestratum" a theraps cichlasomine collected by aquarists for the first time in 1983 by Jean Claude Nourissat, a French cichlid collector and keeper. Is there one or two Cichlasomines living in the lake?, does it holds endemic or widely distributed species?, would it be possible for us to get the "pink fenestratum", said to live among the rocks and being very hard to collect?, those were fascinating questions to find their answers and so we decided to try.
Don and I scheduled our trip for one week at the beginning of May, the ending part of the dry season. As you may have read to boring if you are fond of fish collecting articles, the ending part of the dry season gives you the lowest water levels, besides of clearer waters, easier access to water bodies and no insects flying around avid to bite your flesh, all this advantages are more than convenient for a trip of this nature. Another advantage not so obvious is the fact that most cichlids breed in the wild precisely during the months of low water levels, when the water is warmer, clearer and it's flows levels and rates are no so likely to change abruptly from one day to the other. For a collector this may be crucial for the reason that sometimes your only chance to get enough specimens of hard to collect cichlids is stealing some fry from breeding pairs.
Once Don arrived to México city international airport one Friday noon, we headed straight to the east on my pick up truck to try to reach our farther projected spot that same day, which we did after ten hours of travel. It was the town of Matias Romero in the southern part of the Tehuantepec Isthmus, the mayor human settlement around. Not a big town, Matias Romero holds a population of around fifty thousand people, mainly indigenous descending. Economy mainly spins around cattle raising in the fertile Isthmus lands as well as works derived from the huge modern cement factory in the proximity of the place. Once we arrived to Matias Romero we got a room in a hotel on one side of the trans-isthmus highway 185.
For the first part of our travel we had decided to collect in the southern headwaters of Rio Coatzacoalcos where six cichlids have their natural range: Cichlasoma (Theraps) regani Miller 1974, Regan 1904, all six very beautiful cichlids.
One of our main targets to collect was Cichlasoma (Thorichthys) callolepis, a rare beauty native to Rio grande headwaters and know only not too long ago solely by two preserved specimens at the British museum of natural history, described by Regan in 1904 and collected around Santo Domingo Petapa in the southern headwaters of Rio Grande in the Coatzacoalcos river system. This cichlid however so far hasn't reach cichlid fanciers around the world and we pretended to change this.
On our first trip to this zone I had been surprised by one different Thorichthys that came out in the net among several specimens of Cichlasoma (Thorichthys) "helleri" after one casting in Rio Malatengo (95 00'W.LON.,17 05'N.LAT.), another southern tributary of Rio Coatzacoalcos 20 kilometers north of Matias Romero. This distinctive fish did not bearded the black operculum blotch present in most , and I recognized it the same as a Cichlasoma callolepis newly preserved specimen photographed by Jack Schultz and show in Rainer Stawikowski and Uwe Werner's "Die Buntbarshe der Neuen Welt -Mittelamerika-", page 225. After we got this fish, Don and I tried unsuccessfully for several hours to get a second specimen, but our efforts proved futile. To make things worst, our specimen died shortly after collected, I presume because abuse we made on him taking him many photographs.
Further investigation took us to some University of Michigan papers written by Robert Rush Miller and Bernard C. Nelson in 1961 on Cichlasoma callolepis, with detailed description of the fish and collecting site. Doctor Miller and Jack Shultz during February of 1959 collected 43 specimens in the headwaters of Rio Grande near the crossing with highway 185.
On our first day at the zone we woke up early and went first to Santo Domingo Petapa north of Matias Romero and from near the creek's spring we followed it down going through the little towns of Congregacion Almoloya, Estacion Almoloya and El Ajal to the crossing of the river with the trans-Isthmus highway 185 fifteen kilometers north of Matias Romero (95 01'W.LON.,16 43'N.LAT.) We spent two days collecting in the area casting over and over again in different locations down Rio Grande to the town of Rio Grande, after whom the river got it's name, we also collected in Rio Malatengo eighteen kilometers north from Matias Romero by Highway 185, and there we found the same six cichlid species. Weather was warm with sunny skies and rivers level was on it's lowest, with no heavy rains registered so far in the year.
The Rio Grande is situated in a small mountain range and it is beautifully surrounded by tall trees, At the time we visited it was as shallow as thirty centimeters in the rapids averaging no more than three meters wide and bearing sandy to rocky bottoms, banks were a maximum of twenty meters wide and no more than two meters deep with muddy to sandy bottoms, the river has plenty of driftwood and dead leaves on the floor and boulders are found in the rapids, overhanging vegetation is present along most of the it's edge. Water (Ph 8.0, GH 15 , KH 15 ) was warm around 28 C, semiclear with a greenish hue and with visibility averaging around two meters. Chemical measurements we took this time corresponded closely to what we had get on our first visit to the place (Ph 7.8, GH 16 , KH 13 ).
Snorkeling at the zone showed us the astonishing assortment of fish fauna present in the river, besides the six cichlid species, we could observe several beautiful livebearers, catfish, characid, goby and several other fish unknown to us. According to Dr. Robert Miller there are eighteen fish species in eight families at the place: Characidae (Axtyanax), Pimelodidae (Rhamdia), Belonidae (Strogylura), Poeciliidae (Two mollienesia species, Pseudoxiphophorus and two species of Poeciliopsis), Atherinidae (Archomenidia and Xenatherina), Mugilidae (Agonostomus), Eleotridae (Gobiomorus) and Cichlidae (Six species).
Cichlasoma (Thorichthys) callolepis were scarce at the area, ratio between them and the sympatric Cichlasoma (Thorichthys) "helleri" favored to this latter by at least thirty to one, we could observe them sharing the same parts of the river, and although we saw many "helleri" breeding pairs, we unfortunately couldn't see any Callolepis loving couple, I suppose we were too late in the breeding season and rains could be expected from one moment to the other, many small three centimeters Thorichthys around confirmed my thoughts that breeding activity must peak around January. Thorichthys breeding pairs were always seen around or among tangles of diftwood branches where they could easily find cover from larger enemies, The larger males we saw were about twelve centimeters of total length and females normally half to three quarters that size bearing a distinctive blue ringed black blotch in the middle part of the dorsal fin. I observed pairs in small breeding colonies herding not more than two hundred babies each, little Thorichthys gazing on sunken leaves or organic substratum. Couples always kept very close and did not move around with the fry, but instead they remained at the same place even in sight of potential danger. In this regard they reminded me of other species of colony forming pairs like northeastern México Herichthys which hide their fry in the substratum or under sunken leaves for protecting them rather than moving them from place to place looking for shelter.
In deeper zones I could observe in the open some Cichlasoma (Theraps) "guttulattum" pairs herding their fry which numbered by the hundreds, in this case males were much less brave than the Thorichthys and fled as soon as I got near them, leaving their fry behind. The most distinctive cichlid pairs by much were those formed by Cichlasoma (Parapetenia) salvini couples with their conspicuous beautiful bright yellow and red with black markings coloration, notwithstanding males did not were any braver than Theraps and I rarely saw any one near the fry tending females, in their case I observed them always close to vegetated zones in the shallows were they looked for cover as soon as danger threatened (My ugly face of course).
The highlight of the day was our discovering of a Cichlasoma (Theraps) regani female with about three hundred one centimeter fry hiding among shore's overhanging vegetation. A hand net was at this moment our most powerful collecting tool saving us hours of casting for this scarce beauty, we nevertheless were also able after hundreds of net throwings to get six eight to twelve centimeters individuals now doing quite well in one of my tanks.
During our time there we talked with the friendly people around, they told us about the common names they use for some of the fish, we found out Cichlasoma (Paraneetroplus) bulleri is called "Corrientera", an Spanish word referring to the cichlid habit to live in currents. However all other cichlids were just referred as "Mojarras" with no specific name to tell them apart, although they agree there are six different native species, I just believe the people we talked to didn't know all the fish names. Small cichlids were however called "Chilegua" and Poecilids referred as "Bilulos", both indigenous terms.
But you can't always get what you want, at least not all what you want, and this was the case for us with Cichlasoma (Paraneetroplus) bulleri, one of our main targets of the trip and our biggest disappointment. Although present in the river in good quantities, it proved to be too smart to us, we just could get a single small specimen which got untangled in the net and eventually perished. We weren't also able to see any breeding pair, this last wasn't too surprising because they like to breed in fast flowing water among river boulders, and this kind of environment wasn't very common at the place we were collecting, I think it is more usual going down in the river. We could watch however large beautiful specimens swimming in fast flowing parts of the river, but those areas were too full of large stones and driftwood to allow us to use the casting net properly. Large males were around twenty five centimeters length and showed a head and forehead sprinkled with many beautiful blue dots, staring their beautiful appearance made us fill up with greed for them, but our impossibility to get them gave us a reason to come back to this beautiful area some day.
At the end of our two days stay in the zone we had collected enough specimens of all cichlid species but the bulleri. It was then time to leave and so next very early morning we packed up our fish and departed northwards to the city of Acayucan in the northern part of the Tehuantepec Isthmus.
During our trip we stopped and collected in small affluents of Rio Coatzacoalcos where we found basically the same Cichlid species, though we didn't see any Cichlasoma (Thorichthys) callolepis, Cichlasoma (Paraneetroplus) bulleri or Cichlasoma (Theraps) regani again, but as they are low numbered species and we didn't snorkeled at those places, that is not indication they are not found also there.
We were tempted to stop at Rio Jaltepec crossing with the 185 highway, my friend Rainer Stawikowski told me he and some friends had collected small individuals of Cichlasoma (Paraneetroplus) bulleri upper that river in very shallow water by means of shoveling the bottom boulders with a small seine net, this is also documented in an article by Uwe Werner titled "In search of Mojarras (Part II)" that appeared in TFH magazine March 1987 issue. That could have been our last opportunity to get the fish but we decided to quit that possibility because the day was getting hot and the fish we were transporting could have suffered from that. So rare fish still remains rare.
Day was getting hot as we crossed the low flat lands of the Isthmus, vegetation was plentiful and a loud noise made by insects in the trees could be hear, environment was very humid and the sun started to strike us with all the force it uses in tropical zones. We however arrived to Acayucan and after a while were able to settle in a nice hotel down town, there we placed our fish and proceeded to water changes to cool down water.
From Acayucan that same day we headed northwest by highway 180, we had planned to collect in northern affluents of Rio San Juan, a mayor river of the Papaloapan river system, we had left Rio Coatzacoalcos basin back, so we already were expecting different fish species.
We reached the first river, a tributary of Rio San Juan (94 57'W.LON.,18 02'N.LAT) not too long after we left Acayucan and went down the highway bridge to collect, the river runs inside a small rift on a black volcanic rock bed, it was around ten meters wide at the zone and profundities in the banks were over the three meters mark, water was warm around 32 C with a greenish hue that allowed small visibility, so we decided snorkeling was useless. Nevertheless we have learn by experience that darker water provides more colorful fish, a feature which I believe fish need to show themselves to mates and competitors, this place wasn't an exception, after the first castings we were delighted by a very beautifully colored Thorichthys in our nets, holding deep red and yellow areas on its flanks going high on the ventral region, other additions were a beautifully colored Cichlasoma salvini and (Günther 1860). Mexican rivers livebearer species richness wasn't also an exception here, and beautiful poecilids, swordtails and heterandias fell also in our nets. In spite of our excitement, the species we got there weren't at all new for us, we had collected them in our previous trip in Rio Xochiapa (95 42'W.LON.,17 09'N.LAT.) a southern tributary of the same Rio San Juan, we called the Thorichthys "East Papaloapan Thorichthys" that time and we kept using that name for the fish we got this time, I should point out that we have collected two more forms of Thorichthys in Rio Papaloapan rivers. In Rio Obispo (95 53'W.LON.,18 02'N.LAT.) (PH 7.8, GH 11 , KH 8 ), an affluent of the Papaloapan near the city of Tuxtepec one hundred kilometers west of the place we were, we collected what we consider (Meek 1904), a larger bluish Thorichthys with different snout morphology, we collected also a similar Thorichthys in Rio Tonto affluents west of the Papaloapan system and about forty kilometers west from Tuxtepec. It most be noted also that Rio San Juan merges Rio Papaloapan in the proximity of it's mouth, and so it is perhaps sufficiently far and isolated from the area near Tuxtepec to allow different Thorichthys forms to evolve from common ancestors.
After a short time at the river we had enough specimens to take with us and so we quit collecting, what made easier to collect them here than in Rio Coatzacoalcos was precisely the darker water, in this kind of environment cichlids can't see the casting net as is falling over them and so they don't flee away. Clearer waters are much harder places to collect, specially the nervous fish species.
As we had still about two hours of light for that day, we kept going westwards by highway 180. After driving thirty kilometers we got to a town named Hueyapan de Ocampo (95 04'W.LON.,18 07'N.LAT.) about forty five kilometers south of the Catemaco crater lake by highway 180, another tributary of Rio San Juan crosses at the skirts of the small town, local people call it Rio dos caños though in the maps it holds no name, there is an easy access to the river in a way of a pavement road to the edge. Rio dos caños was a nice place to collect, more than that, it was our best election of the trip. It was late in the afternoon and people was off from work with the next day free because of labor day holiday, many persons were taking a bath or just making pick-nick near the river bed trying to escape from the heat and taking a leisure time. Water (PH 8.0 GH 4 , KH 5 ) was greenish and warm over 28 C. The river was an average of ten meters wide with perhaps twenty meters in the banks, despite the fact pools weren't plentiful for the reason the river has a fairly high gradient at the place, so a moderately rapid flow was the rule, boulders were found in the river bottom which was around one meter from the surface with deeper zones to two meters.
We unpacked our nets and started casting, first cichlids to show up were the same as those we had found previously that day, not surprising in view of the fact that both rivers are tributaries of the San Juan river. However, I suddenly saw a fisherman working one hundred meters down the river and I approached to talk to him, at my staple question of "Cuantas clases de mojarra ahí en este rio?", (How many cichlid species in this river?) he surprised me with a "four" answer, he then told me "Pico de gallo" (Roster peak) referring to Cichlasoma (Parapetenia) salvini, "Testa Colorada" (Red head), no question he was talking about Cichlasoma theraps fenestratum, "Chonga" as they call the Thorichthys specie in the San Juan river and finally he said "Corrientera".
I had suppose often a Paraneetroplus specie should habit in Rio Papaloapan, and I had read about and saw a photograph of a preserved specimen individual that was originally collected in the area around, but I had never had the chance to prove it myself, so at this man statement I was quite excited. I asked the fisherman if he has got any one of those last so far and couldn't stop my exiting when he told me "sure, I have it right here" pointing to his fish bag, I immediately got into the water to see what it looked like, and there it was, the fish I had seen pictured by Dr. Robert Miller as Cichlasoma (paraneetroplus) nebuliferum in Werner's and Stawikowski "Die Buntbarsche der Neuen Welt Mittelamerika-" book page 103 in front of my eyes, I ran to tell Don about it. Though by this time it was dusk and we had to stop collecting, but surely we will come back next day to try to get this fish ourselves.
Further investigation after I got home led me to a copy of Cichlasoma (Paraneetroplus) nebuliferum original description by Gunther published in the Field Columbian Museum Zoology Volume V book, although with no drawing of the fish. It seems the cichlid was first collected in San Juan Evangelista, a close-by little town at the edge of the river that got his name after it, the same river we were collecting. I read the description and made comparisons with adult specimens I keep in aquarium, it proved to me the fish corresponds in every issue to what is described in paper, besides with the preceding mentioned photograph.
When we returned to the place the next day it was labor holiday afternoon and many people were swimming in an upper river pool, so water was cloudy by people action, this proved fantastic for casting such a fast and smart fish and after three hours we have got four adult specimens, always in fast flowing water. We couldn't although use the snorkel at the river that day because of the aforementioned cloudy water, and as we wanted to do it we returned for the third time the day after early in the morning. This time water was clear enough with a three meters visibility range, so casting for the cichlid proved futile, I however couldó snorkel at the place.
Then I was able see many Cichlasoma (Paraneetroplus) nebuliferum swimming among the boulders in rapid flowing water, they were green dashes passing next to me. Looking carefully took me to several fry tending pairs not immediately obvious to the beholder. Pairs are mostly located under the shadows of river adjacent large trees in fast flowing water areas no deeper than one meter, males an average of twenty centimeters long and females slightly smaller. Though males and females are very brave and do not dash abandoning the fry to their luck, parents swim very fast in large circles around them and you can hardly differentiate pairs from normal individuals if it's not for a slightly darker coloration and the fact they circle the same place over and over, fry numbering around one to two hundred individuals per pair immediately after feel any threat scatter and hide behind boulder stones not showing themselves until they feel secure, this fact make the fry hard to spot. So I had to move slowly to be able to observe them, not to mention collect some with a hand net, which proved quite a task. I observed the fry as well as adult specimens of Cichlasoma nebuliferum grasping at the stones algae covered surfaces together with poecilids for feeding. Nevertheless, after a while we had been able to collect about forty fry from several pairs and then we felt our trip goals had been surpassed.
Extra underwater observation at the place showed me that the rest of the cichlids in the habitat showed similar behavior patterns than their equivalent species in Rio Coatzacoalcos. Cichlasoma "theraps" fenestratum breeding pairs were located in the deeper areas, always with hundreds of little babies moving from side to side. Thorichthys pairs in shallow zones with muddy bottoms among protective sunken tangles of tree branches herding no more than two hundred fry and staying always at their territory. Finally Cichlasoma (Parapetenia) salvini pairs also among vegetation or driftwood tangles, males never showing themselves in the close vicinity.
On labor day morning we visited the Catemaco lake in the southern part of the state of Veracruz 81 kilometers northeast from Acayucan. This astonishing beautiful lake 8 kilometers wide by 11 kilometers long (88 square kilometers) with it's twelve little islands is situated inside a volcanic crater at 338 meters over sea level in a small range of volcanos close to sea shore, about 7 kilometers south from the Gulf of México. An unusual thing about this lake is the fact that the small volcanic range in which it is found is located in the middle of plain lowlands with the closest mountain range over one hundred kilometers away. The city of Catemaco is found in the northern part of the lake and it is habited by around 25,000 people, all around it's shore small groups of houses or little towns are located having as main productive activities fishing and agriculture, "Catemaco" word meaning does reference to this fact, from Náhuatl language "Where the houses are scattered". Catemaco lake fishermen comes out every morning in individual canoes from where huge casting nets are thrown over the calm early morning lake surface, providing a beautiful sight to visitors, cichlid fishes are the goal of this people. Later in the day when sun comes high fishermen return to their towns were women wait for them at the shore to take care of the daily catch averaging two kilograms of fish, The day's capture is then taken to be sold at Catemaco market place. Large dragging nets or other massive methods of fishing are not allowed as a mean to protect Lake's people mean of support and cultureó and also to protect the biological balance of the lake.
We visited the southern part of the lake getting to Catemaco from the south by highway 180 (95 04'W.LON.,18 21'N.LAT.). Water at that zone (Ph 7.8, GH 4 , KH 5 ) was turbid with suspended grey basaltic dust particles even in spite of the fact that no winds were present in the early morning, so underwater visibility was almost null at least at the shore's adjacent areas. Pendents were very slow and in the beaches sometimes fifty meters inside the lake profundities didn't surpassed one meter, some zones along the shore were rocky with round black basaltic rocks present, those are the areas where the Cichlids are found, and the zones we started casting at. The large boulders made casting difficult, but not impossible, and after a while the first cichlids started coming out the water, Those were the type called "Conchero" by local people, the pink "fenestratum", though in it's normal coloration.
We noticed the fish as morphologically different from Cichlasoma (Theraps) fenestratum, perhaps it's ancestor. I believe this lake could have been in the past open to the close Papaloapan river system, from where the first fish populated the basin, all the fish we collected seemed descendants from Rio Papaloapan species, but with a long evolution time putting them apart, poecilids called "Cuatopote" by local people were different from those found in Rio San Juan affluents, so a beautiful Xiphophorus specie of gray coloration. We collected besides two characinids species, at least one of them Axtyanax, one of them called "Topote" and the other "Tepesca", this last we collected some specimens over twenty five centimeters of total size of the with very long anal and dorsal fin filaments, these fish is a real beauty. "Topote" variety is the morphologically closest to the Axtyanax specie living in Rio San Juan, but reaches a largeró size, I could collect individuals over twenty centimeters long. I was fortunate enough to be invited by a fisherman to join him in his canoe for fishing, he took me close to some rocky areas where I could get enough pink theraps for taking back, I was also able to get a strong pink theraps specimen, some specimens showed enlarged lips that I could not help to find related to the Cichlasoma citrinellum (Günther 1864) biology, not just because of this feature, but also because of the color changes in the Theraps specie, fishermen don't doubt the fact that very pink individuals are the same fish as the normal colored ones, we were told they all are born gray from mixed colored breeding pairs and then many change color sooner or later, the actual fact was that most of the specimens we saw were the normal type. What is exactly in this kind of environment as in the case of the Nicaraguan lakes that leads the cichlids to develop so similar biological patterns?. Larger lips are thought to be developed by the fish habit of grasping volcanic coarse rocks for algae, a feature is loose by captive specimens after some time. And the oligomelanic pattern, perhaps a way of the fish to show dominance, Dr. George Barlow from the United States has made extensive studies on Nicaraguan cichlids and found that fights among normal and oligomelanic colored (Günther 1864) of the same weight are most of the times won by oligomelanic specimens, this could be an equivalent feature to the development of muchal humps in territory forming individuals of Cichlasomine species like northeastern México Herichthys in which after territory is strongly hold by a pair the hump fades.
All fishermen we talked to agreed to the fact that two Theraps types are found in the lake, the only two native cichlid species found, the other specie is called "Mojarra blanca" (White Mojarra), the most precious specie at the market place, it is said to habit the deeper areas of the lake where they breed, I was told this specimens are never found near the shores, that fact placed them out of our reach because of the small size of our casting nets and lack of boat. We were able however to see some very large individuals cough by fisherman and they seemed to us pretty similar to normally colored pink theraps, though colorless and with a higher body, we were told there are also small specimens of this fish to our suspect that fully sized pink theraps could loose pigmentation.
In the lake introduced Sarotherodon are also to be found and comprise part of the fishermen daily catch, although I was told the least appreciated specie, which commands the lower price at the market place. Antonio Hernandez Rolón in an article titled "A pink form of Cichlasoma fenestratum" that appeared in Buntbarshe Bulletin 102 (American Cichlid Association journal), writes that Günther 1862, is also found in the lake introduced from Tabasco state rivers, although we couldn't find any indication of this last, he also gives in his article some information about the pink Theraphs.
With this we had fulfill the goals for our trip, and although we still had one day left and plenty of places to be visited, we decided to stop collecting and come back to San Luis Potosí to acclimate our catch before Don could take his part to the United States.
During the course of this article I haven't mention anything about the way we keep and transport our collected fish. Throughout several collecting experiences we have been developing some experience in order to keep more fish alive, and we have found that this may not be as difficult as it may seem. A prove of this is that at the end of this travel we had a survival rate of over 95% of the fish collected. We now understand the main cause of collected cichlid deaths, lack of oxygen. Other important death causes are polluted water, improper fish handling and fights among cichlids. To solve the first problem what we do is collect the smallest number of fish we need, not counting with future losses, we normally get when possible about four to eight individuals of each specie per interested person. We never take fish over twelve centimeters of length which will surely do very poorly, we instead try to get the smallest possible specimens, preferable around five centimeters long. Fish is keep as cool and uncrowded as we can and for this purpose we normally place half filled large fifty liters plastic jugs in an air conditioned hotel room where we run an air line into the jugs with the help of air pumps. In each of this jugs we place up to a maximum of twenty five small cichlids trying always to keep it at half that number. An useful addition to our last trips has been the dosing of a tranquilizer to the water which keeps oxygen consuming and stress causing cichlid fights to a minimum. Water changes are performed at least once per day, but in crowed conditions at least twice.
Transporting of the fish in hot weather is made during late afternoon to mid morning to prevent increase in water temperatures which may easily kill any fish including hard collected rare specimens. We don't supply any food for the large fish although our trips do not normally take more than ten days, fry however has to be fed and we do it providing river collected algae to herbivorous species and powdered dry food to omnivorous ones.
One aspect of collecting previously overlooked for us and that may cause many deaths is the treatment the fish is given just after being collected. The stress caused by taking them out the water is alone in some species cause of death, but even in hardy species you add the fact of getting them with dry hands hurting with this their protecting mucus, keeping them more time than it is necessary outside of the water and finally placing them in a crowded bucket fill of hot water, then you surely are looking for trouble. To make things worst, many times you still add to all injuries made already to the fish a photograph session with several fish jumps to the floor. We release the fish we use for photograph after the process, and we try to do it with the larger fish we may get.
For transporting the fish to the United States Don placed half a dozen fish in ten liters plastic jugs with no more than two liters of water to which he added some tranquilizer, he then placed the jugs inside a cardboard box and tied it up. All fish did quite well.
After all the stress the fish is involved from capture to placement in aquarium many natural occurring and tank resident parasites may find the fish an easy and suitable prey. It is for this reason that an isolated parasiticide quarantine treatment to new arrivals is a must. Isolation from tank resident species it is also a way new fish don't get upset by aggressive and well established fish. However some "dither" fish like large sized livebearers or peaceful characinids are helpful by providing confidence to newly arrived fish, under this conditions fish will normally start eating almost immediately after being introduced into the tank. All this cautions are not means exaggerated and may mark the difference between proper fish establishing or death.
All our fish finally did quite well; Cichlasoma (Paraneetroplus) nebuliferum turned out to be a very aggressive cichlid with a lot of personality and a voracious appetite, the same is true with the Catemaco Theraphs. Cichlasoma (Parapetenia) salvini didn't wait to show their very aggressive nature. Cichlasoma (Theraps) regani is a beautiful shy fish of peaceful habits compared to other Theraps like the sympatric Cichlasoma (Theraps) "guttulatum" or the Papaloapan Cichlasoma (Theraps) fenestratum.
© Copyright 1991 Juan Miguel Artigas Azas, all rights reserved
Artigas Azas, Juan Miguel. (Maggio 27, 1996). "Rare Jewels of the Tehuantepec Isthmus". The Cichlid Room Companion. URL consultato in data Maggio 25, 2013, da: http://www.cichlidae.com/article.php?id=3&lang=it.