Collecting in the Paraná River Basin, Argentina

Collecting in the Paraná River Basin, Argentina, (Part 1)

by Carlos & Noemí Bishop
Edited by Allan James

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This is the first in a series of articles on the collections carried out by the authors in their native environment around the Paraná River in northern Argentina near to the city of the same name, (Paraná City), and also into the Misiones province near Posadas city in the south west zone of the province near the Paraguayan border. I will now hand you over to Carlos and Noemi to take you through their collecting experiences.

e live near Paraná City, which is on the banks of the river of the same name and is 500kms (310 miles) north of the capital Buenes Aires. Around this zone there are numerous creeks, little streams and branches of the river, where I try to collect wild fishes. In this place are very common, various species of Loricariids and Callichthyidae, normally the people call them "Vieja del agua" to any of this species, but not all are the same species.

Last February I went fishing with my wife to the Paraná river, in a place that we had never been before, when we threw the nets on the water we caught various little fishes, at first we believed that we had caught Hypostomus plecostomus, which is very common here, but a second look showed that we had another species of loricariid. We took the fishes to our home and raised them in a 120 l. aquaria (about 26 UK gallon). Then we searched for information about them. We had no luck, we could not find any information, no photos, no name, or no description, so we contacted Allan at www.scotcat.com to try and find out what species this was and this led us on to a friendship which has blossomed and has cumulated in this series of articles which I hope you will all enjoy.

Now ( July 18, 2004) the fishes are 55 mm (about 2 inch) of total large, when we caught them they were 25 or 30 mm (about 1 inch). We feed them with a home made mix that is made with lettuce, peas, carrots, soja floor and a bit of cat food, for the taste. The fishes enjoy this food and take it eagerly, and with this food they seem to grow fine. I did not know the adult size of this species so I asked the people who live near this place, but they do not seem not to know these catfish. In the wild the enviroment was a sand and soil mix, the water pH was neutral and the water was turbid, but no too much (The Paraná river water is never clear). The air temp was about 33 ºC.

Allan has replied on the identification of this species and below are his comments.

<I have had a reply back from Jon Armbruster of the Auburn University Museum Fish Collection, and he is quite sure that it is a juvenile Hypostomus cochliodon from the H. cochliodon group. They have spoon shaped teeth when adult but may not show this trait yet on your specimen. He also mentions that he has not seen such big spots on a juvenile before so I'm guessing that this species from your area of the Paranà River must have this trait , as the specimens that are described are usually from Paraguay. When reaching adulthood there are more spots and they get smaller, and more spread out.>

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Hypostomus cf. cochliodon (juvenile)

We caught another species in the same area as the Hypostomus cochliodon, a species that we thought looked like a Panaque species. Indeed it looks similar, but not the same, in form and colour to Panaque L204-flash pleco- or a Panaque maccus-clown pleco. Where we caught this species was only
5 to 6 Km. from the first collecting site. The size and growth rate are very similar to the Hypostomus cochliodon. We only captured two specimens, but the little one was very tiny and did not survive.

This second pleco actually turned out to be a juvenile Hypostomus latifrons (L 051, L 281) and is also native to Paraguay. This species as it
grows loses its stripes and takes the reticulated pattern of the head right through the entire body area.

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Hypostomus latifrons (L 051, L 281) (juvenile)

The third species that we could not identify is a pleco that looks like a Pterygoplichthys. We caught it in February 2003, when we took it to our
home it was only 25 - 30 mm (about 1"), in the first days it had a rounded tail with a clear edge and a very dark colour, almost totally black. We caught it in densely planted sites with a depth of about 20 - 25 cm (8 - 10 "), and in one occasion, a ditch that was barely 40 cm width and was 15m (45 ft) from a little creek.

From the first moment it loves wood, it spends the time over a submerged branch, and its growth rate was so fast that if we look attentively we can see it grow continually. In a few days the tail had filaments and were pointed and the fishes continued growing and the colour become a bit clear. They continue growing fast after about a year, and then its growth rate slows down.

The most species of plecos are nocturnal or crepuscular species, in occasions quite shy, but these are active all day and are not shy. At this time it has grown to 150 mm (about 6") and its growth rate is much more slow now. We see specimens about 250 mm (about 10 "), we don't know if there are more larger specimens.

We were right in the assumption that it is a Pterygoplichthys species, namely Pterygoplichthys anisitsi. The genus name has now been reclassified back to Pterygoplichthys from Liposarcus due to the work carried out by J.W. Armbruster 2004.

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Pterygoplichthys anisitsi

We caught this Pterygoplichthys anisitsi in two diferent sites. The first one was in the same Paraná river, near (3 to 4 miles) from the site where we caught H. cochliodon and H. latifrons, but this site was much more densely planted, the river was in high level and the water had flooded over the grass in the low banks. In this submerged grass we catch Rineloricaria sp. Corydoras paleatus and Corydoras hastatus with lots of juvenile Hypostomus plecostomus, Characins (Aphyocharax anisitsi, Hemmigramus sp. etc) and a few juvenile Crenicichlas.

The other site was a ditch that is barely 40 cm (16 inch) width and was 15m (45 ft) from a little creek. This creek finished in the Paraná River about 1 mile from this point. In this site we also captured Gymnogeophagus rhabdotus and a Characin, Phyrrulina sp., similar to Copella arnoldi, the splash tetra, and also various juvenile H. plecostomus.

We did not know the water temperature, (the air temp. was about 33ºC) but we guessed about 28 ºC. The pH in the first site was neutral, in the second site we guessed that the pH was more low, due to the submerged dead vegetation and some branches, the water temp. must be higher (about 30 ºC) due to the low water level directly exposed to the sun, and also the water was quiet, with no current due to a dead branch on the creek.

The next species we have is a Sturisoma species, we captured this about 400 or 500 m from the site where we caught H. cochliodon and H. latifrons, in this place there was much more floating plants. The larger plants that we know as "camalotes", are very common in the Paraná River and some times form little floating islands. We caught two of this species, but the little one was almost a thread and did not survive. We see this catfish in the local aquaria shop, they are about 10 inches in adult size, but the colour and profile are the same as our fish, that was captured in February at 2.5 inch length and now is about 5 inch. We guess that is a Sturisoma aureum form, but the dorsal fin is different to the photos that we have.

This species turned out to be Sturisoma robustum which also comes from the La Plata area further to the south and also to the north of us in the Misiones area, and may also be found in Brazil and Paraguay. Today all the water streams to our south in the La Plata zone are contaminated, it is very sad, but it is an actual reality. I know La Plata city and its surroundings to the north, I do not believe that there are many fish alive there, may be to the south ..... As I said, it is very sad. I hope this species lives on in other sites.

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Sturisoma robustum

References: Armbruster, J.W, 2004. Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae.

All Photo's by the authors.

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