Shane's World Right Geography Right The Venezuelan Diary Series, Part 15 • The hunt for Farlowella acus

Article © Shane Linder, uploaded January 01, 2002.

On 5 July 2001, I traveled to Aragua State in search of Farlowella acus. F. acus has a very small distribution range and is known only from the Lake Valencia drainage system. Sadly, most of this drainage is heavily populated with the result that the majority of the rivers and streams are very polluted. Previously, I had driven along the eastern end of the lake, from Maracay to San Francisco de Asis, and was unable to locate a single viable collecting location. However, I was not ready to give up and so I spent hours with a map tracing the courses of the rivers that flow into Lake Valencia trying to find one that might still be clean.

I located two possible collecting locations northeast of the lake, the headwaters of the Rio Aragua above the town of La Victoria and the Rio Guayabita above the village of the same name. The map showed no towns upstream of the collecting locations, and I had driven past the headwaters of the Rio Aragua before and remembered that it appeared clean. The first collecting location was at the confluence of the Rios Aragua and Macanillal near the village of Santa Rosalia about 5 km north of La Victoria. The water at this location was crystal clear and about 70F. Both rivers were 15 to 20 feet wide with an average depth of 8-10 inches with occasional pools and cut banks up to three feet deep. The substrate was fine sand and gravel in the slower portions and fist-sized rocks in the riffles. The banks were lined with bamboo and in many places the bamboo branches reacheddown into the water. There was very little driftwood, since the area is mostly treeless, and there were no aquatic plants.

Knowing the typical habits of Farlowella, I first sampled the overhanging, and partially submersed, bamboo leaves near the bank with a two by three foot hoop net. The first try brought up only a small Rhamdia sp. and the second a two-inch pike cichlid. My third scoop through the bamboo, however, struck gold and contained a single six-inch Farlowella acus. I immediately knew that I had the right fish when I saw the very short and broad rostrum. This Farlowella is a very pretty red-brown after capture, but turns golden with the two distinct darker dorsal stripes common in this genus shortly after capture.

Luckily, F. acus turned out to be the most common fish in the river and in 45 minutes I had captured over 25 specimens. I noted two distinct populations in regards to size. About half of the fish measured 2.5 to 3 inches SL and the other half all measured 4 to just over 5 inches SL. The smaller fish must represent last year's fry while the largest are all full grown adults. All of the largest specimens (5 inches and over) are adult males. Since it is still early in the rainy season, and thus the breeding season, all adult males possess a full growth of odontodes along the rostrum.

I sampled about 200 feet of the river's course and only found F. acus among submersed bamboo leaves in areas with a moderate current. The water had a pH of near neutral and was very soft. Perhaps due to the low amount of nutrients, there was very little algae growth in the river. I believe that the diet of F. acus probably consists aquatic insects and larvae found on the bamboo leaves, as well as (possibly), the bamboo leaves themselves. The only other fishes captured at this location were guppies, a species of pike cichlid, L122, a Rhamdia sp., and an unattractive Creagrutus sp. of tetra.

Shortly after I started collecting, a group of local men came to the river to collect rocks for the plaza in La Victoria. Interestingly enough, none of them had ever seen Farlowella acus and they had no common name for it. One guy stated that he had lived in and around Lake Valencia his entire life and had never seen F. acus before.

F. acus is a very distinctive Farlowella with a short blunt rostrum similar to that of Sturisoma spp. All of the hobbyists catfish books that I am aware of misidentify this species (see Burgess, 1989: 747; Baensch, 1987: 488; Kobayagawa, 1991: 53; Axelrod, 1987: 451) and it is extremely unlikely that F. acus has ever been imported for the aquarium hobby. This is very sad, since given its endangered status, a captive breeding program should be undertaken by the hobby.

According to Retzer and Page (1997), there are two distinct populations of F. acus in the Lake Valencia basin. One population is from the northern and eastern tributaries and a second from the Rio Torito and southern tributaries. The populations can be differentiated by their caudal markings and the relative position of the eye.

The second collecting location was the Rio Guayabita near the village of Polvorin about 8 km north of Turmero. This river was an example of what can happen to the habitat of F. acus. Small orange orchards populate the valley along the river. Unfortunately, the farmers have taken to using the river as their private trash dump. I observed the rather strange sight of a group of L 122 rasping at algae on an old vinyl car seat in the clear water. After about 30 minutes of sampling I only turned up a few L 122 and some guppies, both of which from my experience, can adapt to fairly polluted waters. The tetras, cichlids, and Farlowella were all absent from this environment.

Recreating the F. acus biotope: Although it is unlikely that this fish will ever be imported, this same information applies to Farlowella vittata as well.

A 20 or 30 gallon "high" tank should be set up with a substrate of sand or small gravel. A power head with a sponge prefilter should be placed in each rear corner to provide a moderate current as well as biological filtration. If the aquarist has access to bamboo, simply cut a number of bamboo shoots, with the leaves still attached, and arrange them along the back and sides of the tank with the bottom of the shoot buried in the substrate. The shoots can then be replaced every few months after the leaves turn brown and start disintegrating. Bamboo shoots, especially in a tank with bright light, actually live a long time even under water. Alternatively, the bamboo can be replaced with a maze of branches or ton kin reeds.

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

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