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Seeking The Peacock Bass

Cichla species are monster fish that need large tanks.

By Robert J. Goldstein |

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A monumental 398-page report by Sven Kullander of the Swedish Museum in Stockholm and Efrem Ferreira of the Aquatic Center of Biological Fisheries in Manaus took up the entire December 2006 issue of Ichthyological Exploration of Freshwaters (17:4). Their article, "A review of the South American cichlid genus Cichla, with descriptions of nine new species (Teleostei: Cichlidae),” is the most important paper on American cichlids in decades. Kullander and Ferreira raised the number of peacock bass (Cichla) to 15, using detailed analyses based on morphometric, meristic and distributional data, and computer-assisted phylogenetic tools to graphically assemble the smallest self-perpetuating populations, known as tokogenetic groups (Nexus Data Editor, PAUP, MrEnt). 

 

And it’s not the last word. Kullander’s and Ferreira’s purpose was to collect from all known populations from throughout the Amazon and adjacent basins to determine which names should be used for the distinct populations on the basis of body part variations; these variations tell us what is new (or old) and unique, what is shared and how far back the variation can be traced. Groups that share some variation on a theme must have common ancestry. This phylogenetic analysis allowed the authors to construct distinct and discrete self-perpetuating groups, but they recognize this is a starting point for further investigations using, for example, nuclear or mitochondrial DNA analyses.

 

Peacock bass
Peacock bass. Photo by Ianare/Wikipedia
It’s step one in a long series of investigations. But now we’ve got the groundwork, and if past investigations of other groups are an indicator of what’s to come, we’ll probably see most of these species names validated, more detected or discovered, and we’ll be able to refine the history of Cichla. Kullander and Ferreira determined species groups within the genus and how the species are related — a good place to start.

Details of the Study

Many of us are familiar with the names Cichla ocellaris and C. temensis, and have seen other names over the years. But this paper demonstrates that markings are more variable and complex than anything previously published (markings often vary greatly within a single species, sometimes between the upper-river fish and lower-river fish, and sometimes even within a single location in a river). The authors constructed a guide to the diagnostic markings and other characteristics for Cichla species from different drainages, but they warn that you must measure and consider everything; just a few other factors to look at, for example, would be marks on the upper gill cover and the caudal fin shape. The combinations of traits are reliable indicators — not the existence of one or two features. 

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They studied more than 362 individuals, counting and measuring scale counts above and below the lateral line, dorsal spines and soft rays, anal rays, pectoral rays, number of vertebrae, gill rakers on the first gill arch, caudal peduncle length and depth, interorbital width (distance between the eyes), head and snout length and depth, body depth and dorsal spine length. They also considered markings (in part from photographs), such as ocellar (white-ringed black) marks on the body, vertical bars, a lateral band or lateral blotches, caudal and abdominal blotches, rows of light spots on the side, postorbital (behind the eye) marks, existence of an occipital bar (a mark from the gill cover over the nape of the neck), and how these occurred or not in different populations. They also studied specimens from 15 major museums throughout North and South America and Europe. 

They determined that 15 distinct species could be identified now (including the new ones), and probably 20 or 30 additional species will be recognized when more collections and data fill the gaps. Some species are widespread, and others are restricted to one or few rivers. One species, Cichla mirianae, is confined to upper tributaries of the Rio Tapajos, where I’d been years ago. At the time, I couldn’t decide which Cichla species I had. Now that it has been determined that only one occurs in the upper Tapajos, there’s no question that I had Cichla mirianae

The Habitat and our Fishing Camp

Several large rivers drain tropical South America. The Amazon is the deepest and largest river in the world. It is surrounded by the Tocantins to the east, the Parana to the west and the Orinoco and Piraiba and smaller basins to the north. The Amazon’s 11 major tributaries are the Negro (including the Rio Branco), Xingu, Madeira, Tapajos, Solimoes, Ica-Putumayo, Jupara, Jurua, Maranon, Purus and the Ucayali. The Solimoes joins the Negro at Manaus to form the main stem of the Amazon. The Negro is the most important tributary from the north, and has a seasonal connection to the Orinoco — an otherwise separate basin. The larger rivers from the south include the Xingu, home to spectacular loricariid catfishes, and the Tapajos immediately west. 
The Rio Sao Benedito is far upstream (south), located at the southern rim of the Amazon basin. It is one of several parallel small rivers that originates in the southern highlands at the rim of the Amazon rain forest depression. The remains of these forested highlands are being cleared and burned for cattle farming, though the government is trying to stop it.

We had a fishing camp on the Sao Benedito, about as far up the Rio Tapajos basin as you can get. The Sao Benedito is narrow and black like St. John's River in Florida, and its edges are lined with white and purple water hyacinths, various reeds and water-tolerant trees. At the camp, the river drops about 10 feet in 1,000 (a 1-percent grade) as rapids separate the upper from the lower river. During the rainy season, the rapids are submerged, and there is no barrier to migration.

Carlos Munhos Arroyo is the owner of the Posada Salto Thaimacu, a fishing camp located just above the rapids. From the camp, we could take a motorized boat upstream or downstream on the Rio Sao Benedito to fish the main stem of the river or the myriad backwaters and tributaries that lurked under the forest cover. 

As is typical of many upper tributaries on slopes, the Sao Benedito flows swiftly, carrying logs and dislodged hyacinth mats. Black at midstream, it is fed by black seepage and clear (whitewater) streams. Every habitat is different in terms of water color, depth, temperature, shade, bottom and surrounding vegetation, sunken logs and other debris, sand or silt or mud on the bottom. The habitats also varied depending on whether we were on or above the rapids or in a backwater or tributary.

Fishing with knifefish as live bait (and then cut-up piranha when we ran out of knifefish), we caught dozens of peacock bass and piranhas (which will take any bait, including cut-up piranha). At the time, I could not identify the species of Cichla but assumed I had at least two kinds. Carlos told me they caught three kinds in this river, but adjacent rivers had more.

According to Kullander and Ferreira, the only Cichla in the upper Rio Tapajos system (which includes the Rio Sao Benedito) is Cichla mirianae, and we were catching color forms of only this fish. Based on what we saw or caught in the river, it probably eats Apistogramma, Leporinus like cyprinids, penguin and other tetras, cory and loricariid catfish, some piranhas, tree frogs and tadpoles, knifefish, butterflies, dragonflies, bees, grasshoppers and small birds.

Their large mouths can probably engulf just about anything. The only bigger fish in the river are huge catfish, and the only predators on both are fish-eating birds and caiman, which probably prefer turtles. We caught few Cichla mid-river and caught more in quiet backwaters. When hooked, they’d surge under the hyacinth mats from which we had to coax them out slowly (all were released). 

Cichla mirianae is known from the two upper tributaries forming the Rio Tapajos (the Rio Teles Pires and Rio Juruena) but not north (lower) in the Rio Tapajos main stem. It also was recorded from the nearby upper tributaries of the Rio Xingu, suggesting that seasonal high water connections might occur as they do with the Orinoco and Negro. The only other Cichla from the Tapajos drainage is C. pinima, another new species, from the lower main stem of the Tapajos and tributaries. This same fish also occurs in the Rio Curua-Una, the Rio Xingu, the Rio Tocantins, the Rio Capim and the Rio Amazonas (the Solimoes downstream of Manaus), again suggesting seasonal high water connections.

Do any other Cichla occur in the Rio Sao Benedito? Kullander and Ferreira didn’t have specimens from this river, so it’s good to keep an open mind. Meanwhile, all the fish we caught were presumably C. mirianae.

Yet More Cichla?

The aquarium hobby is more than 100 years old, and in all that time, we thought we had at most two kinds of peacock bass. In the past few years, the sportfishing community has confused the common names of these fish, and now use "peacock bass” to describe Florida oscars. Aquarists have also abused the names of peacock bass by not recording the rivers, streams and lakes in which our aquarium fish were collected, and not recording markings and measurements in greater depth. By the time Kullander and other ichthyologists are finished with this genus, there may well be 50 species of Cichla. 

References 

Zuccon, A., and 
D. Zuccon. 2006. MrEnt v 1.2. Department of Vertebrate Zoology 
& Molecular Systematics Laboratory, Swedish Museum of Natural History, Stockholm.
Several species of pacu and piranha are abundant in the Rio Sao Benedito. Piranhas, such as Serrasalmus notatus, are the most frequent catch here.

The Cichla Species List

This is Kullander and Ferreira’s list of Cichla species thus far (don’t forget the 20 or 30 others yet to be named).
Cichla ocellaris
C. orinocensis
C. nigromaculata
C. monoculus
C. kelberi
C. pleiozona
C. mirianae
C. melaniae
C. piquiti
C. thyrorus
C. jariina
C. pinima
C. vazzoleri
C. temensis
C. intermedia

A Glance at Cichla

What do the Cichla look like? Kullander and Ferreira provided photos of all, and you’ll find many more in aquarium literature, but hobbyists’ snapshots seldom authenticate where those fish were caught. Moreover, several species have been transplanted throughout South America by fishery biologists "improving” local sport fisheries (this has gone on throughout the world). Many hobby photos are of fish collected from different rivers (exporters put fish that look alike into the same box). So, take any identification you see with a grain of salt, unless you know its origin.

Here’s another source: Google "peacock bass,” and you’ll see advertisements for sportfishing camps in South America offering travel packages for peacock bass, giant catfish and piranhas, with links to nature trips for bird watching, orchids and photography. Many of the sites have photos of what visitors have caught, including the local types of Cichla. You can e-mail the site to confirm the picture came from that camp and was not supplied by the advertising agency.  

Cichla extend throughout the Amazon and adjacent rivers of tropical South America, and many places haven’t yet been studied. They’ve also been transplanted. By searching for fishing camps on different rivers, you can set up an expedition to a place nobody has looked before and not worry about having a group of aquarists or a travel agency set it up for you. Although you cannot legally remove fish from Brazil, take your camera and a glass photo tank, and bring them back in living color on your laptop. You probably won’t know what fish you’ve caught while you are still in the field, but a photograph will save the colors and markings.
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Seeking The Peacock Bass

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Dante    Hyde Park, MA

5/10/2014 2:17:52 PM

A very interesting fishing expedition!

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