Article © Hans-Georg Evers, uploaded April 02, 2010.

Photographs by the author except where otherwise noted.

The team of Expedicion Misiones at the Iguazu falls,
from L to R: A. Villanucci, K. Udomritthiruj, N. Woodward, H.G. Evers

Introductions
Amongst the so-called „phantoms" within the genus Corydoras, that is to say names we see in books as words but not fishes we see as photos or live specimens, there is one species which was described only a few years back in 1983 but yet was still a shadowy figure. Corydoras carlae was named after Mrs. Carla Lindenaar-Sparrius, a colleague of the describers Njissen and Isbrücker in the administration Dept. of the Amsterdam Museum. The species is only known from the State of Misiones in Northern Argentina. The type locality — a "small Arroyo (= river)" - lies between Puerto Iguazu and Bernardino de Irigoyen on the Ruta 101, around 50 km away from Puerto Iguazu. J.-P- Gosse collected the type material in 1977. There is no GPS data for the type locality available a the time of writing.

Since the publication of the first description I was after this species but never made it myself to Argentina. My friend Stefan Körber, probably the leading German expert on Argentinian fishes (check out www.pecescriollos.de), once brought a few live specimens from one of his trips and gave them to Ingo Seidel. Unfortunately these fishes never reproduced but finally I was happy to at least make a picture of the life colouration for an Identification Guide which was in preparation at that time (Fuller & Evers, 2005).

The Arroyo Falso Uruguai in Northern Misiones, January 2010.

In Argentina
One of the goals of "Expedicion Misiones 2010" which was an international group of aquarists visit to the State of Misiones in January 2010 was to find Corydoras carlae in the wild and bring some fishes back for breeding attempts. I was the German part of the team. My friend Neil Woodward of Pier Aquatics in Wigan was the English part. Our mutual friend Kamphol Udomritthiruj from Bangkok, designated fish exporter and guppy lover, had the longest way to come. The three of us were hosted by Agustin Villanucci from Buenos Aires. Agustin is an aquarist since his childhood and dedicated his life to the research on the freshwater fishes from Argentina. Stingrays and the cichlids, especially the genus Crenicichla, are his main fields. Agustin prepared everything perfectly. He arranged the necessary permits for collecting fishes in Misiones and arranged transportation and accommodation. We had a perfect time in Misiones, driving almost 3000km and collecting at many interesting spots. One of the most exciting trips for me was the trip to the biotopes of Corydoras carlae. Agustin collects fishes across the whole of Argentina, and has been doing so for many years and so he knew well where to go to get my eye-rolling "phantoms".

January is normally the time of very low water levels in Argentina. It is the hot summer time when the people leave the towns and cities and go on their holidays. Misiones is embedded between the two huge river systems of the Río Paraná in the West and the Rio Uruguai in the East. Usually at that time of the year one can easily collect fishes even in the big rivers, as the water levels are very low. But what was still "normal" during the last years? Everything is going crazy with the weather, everywhere in the world. This was also the case in January 2010. It was raining cats and dogs in Southern Brazil, Paraguay and Northern Argentina. The rivers were full of water and even the smallest creek was a wild water body with fast running, turbid waters and low underwater visibility. Kamphol and I had brought our underwater camera equipment as we expected wonderfully clear headwater rivers and bright sunshine for excellent pictures. But we found most of the rivers with high levels and no good conditions for underwater photography. Furthermore the collection of fishes was quite difficult and almost impossible in the big rivers themselves. But we had Agustin and he managed to take us to several spots where we could at least find some interesting fishes to collect.

Iguazu Falls - View Larger Map

Saturday, January 21st 2010 was the day we decided to drive to the famous waterfalls of Iguazu. It was a bright sunny day and due to the massive rainfalls upriver the cataracts were fully loaded with water. It was an amazing morning, running along the waterfalls and our cameras had a busy day.

The Ruta 101 from Pt. Iguazu to Bernardo de Irigoyen nowadays runs through two different Natural Reserves. It is strictly forbidden to collect any animals or plants in the Parque Nacional de Iguazu and later on in the Reserva Palmitera in the hills of the Sierra de la Victoria. So we could not check the rivers along this road and trying to find the place where Gosse once collected his type material of Corydoras carlae. But this was not necessary at all. Stefan Körber and also Agustin knew a locality close to the town of Wanda on the Ruta 19 in the basin of the Arroyo Falso Uruguai, Río Paraná drainage. The Arroyo Tirica is also the type locality of the recently described Hisonotus hungy. In the first description of H. hungy Corydoras carlae is mentioned to be one of the syntopic species. Unfortunately all our fishing for Corydoras carlae in the Arroyo Tirica was not successful at all. We found Hisonotus hungy and a few other species but the Corydoras did not show up. There was too much water and there were no sandbanks other promising spots to find Corydoras catfish in that place.

The author collecting Corydoras carlae in a huge field of Echinodorus uruguayensis.
Photo: K. Udomritthiruj

But we did not give up and went on the Ruta 19 until we came to a junction with the laterite road 227. We followed this difficult to drive road — we had no four-wheel-drive but only a little Volkswagen, not really an off-road-car — until we came to a spot where we could reach to the Arroyo Falso Uruguai itself.  The coordinates are S 25°58.427/W 054°15.475 at 667 ft. The almost clear water was fast running over a bed of sand and gravel. Water temperature was 24.3°C, at a pH of 7.9 and the conductivity 71 µs/cm. These parameters, especially the water temperature are under extreme changes. Northern Misiones is known for very cold weather in the wintertime, months June until August. Agustin confirmed to me that he found the rivers then to be very cold, certainly around 15°C and sometimes lower a few weeks in the year. I will certainly have to follow this and give my fishes from that region a cold period of at least several weeks a year. Otherwise it is doubtful that any reproduction can be triggered.

Agustin and I were checking all possible spots for Corydoras without luck until Agustin found a spot with a large population of Echinodorus uruguayensis into which he dipped his net. Bingo! A smile appeared on Agustin’s face and a big female of our so long searched for Corydoras carlae was jumping up and down the net. Now it was on me to go for it and within an hour of hard work I finally managed to get at least ten specimens of this rare Corydoras. Neil and Kamphol later took over and managed to get another five pieces. Amongst the catch I found three specimens which were covered with white tufts, apparently a disease. It was my first time ever that I found Corydoras with any infection or disease in the wild.

A short look underwater:
Fine gravel and sand on the ground and lots of Echinodorus plants to hide in.
This is how the biotope of Corydoras carlae looks.
Photo: K. Udomritthiruj

With our permits we were allowed to export ten specimens of a single species and so I was happy to bring some Corydoras carlae home to Hamburg. They are now acclimatising in one of my "colder" tanks and eat a lot. I hope I can manage to breed them soon and distribute this rare fish amongst Corydoras fans. Corydoras carlae is certainly not a beauty in the common sense. But beauty lies in the eye of the beholder and people know me to have a special attitude towards all these greyish look-alikes.

My thanks go to Agustin Villanucci in Buenos Aires making all this possible and of course to my buddies Neil and Kamphol who supported the crazy German in his attempts to collect another "grey Corydoras".

Some of the collected C. carlae were diseased.

1. Literature cited:
1. Fuller, I. & H.- G. Evers (2005): Identifying Corydoradinae Catfish. Kidderminster/Rodgau
2. Nijssen, H. & I.J.H. Isbrücker (1983): Sept espéces nouvelles de Poisson-Chats cuirassés di genre Corydoras Lacepéde, 1803, de Guyane francaise, de Bolivie, dÁrgentine, du Surinam et du Brésil. Rev.fr. Aquariologie, 10/1983: 73-82

There is further information on this species on the Cat-eLog page.

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