Information Central (c) Larry Larsen
Color/Pattern Changes
 Anyone that has spent several weeks in the Amazon catching peacock bass has
noticed that there are vast differences in the color scheme and pattern on many of the fish. Some may be differnet species while others may be variations
due to habitat or water characteristics or other factors.
Natural hybridization in peacock bass is thought to be very common by some
biologists. Peacock bass, fish belonging to the genus Cichla, are represented by five primary species, according to some sources: Cichla ocellaris, Cichla
monoculus, Cichla temensis, Cichla orinocencis, and Cichla intermedia. However
, in addition to those, there have been another 10 species recognized by some biologists.
Hybridization in nature is considered very common among some groups of
freshwater fish, depending on environmental factors. While a low frequency of
natural hybrids may be expected in the Amazon, it is possible that some hybrids may have been identified as distinct species. In the region, morphological
studies have identified natural hybrids, according to biologists.
I'm sure that Amazon anglers have all seen what they thought were hybrids,
fish sporting features of more than one species of peacock. With that in mind, I received an email from a friend
about an interesting hybrid butterfly/speckled peacock.
 He wrote, "Larry: I thought you might be interested in the attached
photo (shown on right). We had some very experienced anglers on our trip plus the boat manager, and none had seen this color pattern
previously. Two fish were caught with this pattern." I have seen a few similar fish in the San Benedito River in south central Brazil that
exhibited both the butterfly and speckled markings, and I have included as the lead photo one of my pics of a similar fish.
Variation Reasons/Causes
Like most of the peacock species, the giant peacock bass, or Cichla
temensis, occurs in a variation of colors and patterns. The differences between some like the "paca" or striped peacock and the "acu" or 3-bar
, for example, are so distinct that they have often been thought to be two separate species.
 "Throughout its range in lowlands Amazonia, C. temensis, is the largest
and most commercially important of the Cichla (peacock bass) species," says Paul Reiss who is studying and doing extensive research on the fish
. "It occurs in its two distinct forms throughout its range in the Amazon basin, and this variation has been the source of ongoing confusion
among sportfishermen, locals and even biologists."
"The two forms are even referred to by completely different common
names; the "Speckled Peacock Bass" and the "3-barred Peacock Bass" (known locally as 'Tucunare-paca' shown on right and 'Tucunare-açu',
respectively)," he continues. "These common names are descriptive of the respective color and markings, and several possible explanations for
the variation are reflected in popular beliefs. The most common opinion among locals and sportfishermen alike is that the C. temensis variants
represent permanently different individuals within the population."
A less commonly held opinion is that they are separate species or
subspecies. Although not commonly considered among the popular beliefs, a third possibility is that they may be
color changes occurring in individuals within the population. One thought is that the cause of color and pattern
differences in C. temensis variants may be a change within individuals related to spawning or seasonal cycles.
"Specimens are commonly encountered showing characteristics intermediate between the extremes of the
variation, indicating a possible gradual change," Reiss continues. "Specimens of the 3-barred variant are not
observed at a size smaller than that associated with sexually mature individuals capable of spawning.
Observations of nests, spawning sites and fry-guarding parents have not demonstrated specimens of the
speckled variant engaged in spawning or rearing activity."
 Additionally, Reiss noted that color changes related to spawning behavior have been found
in other species of the family Cichlidae, as well as other fishes. The hypothesis was tested by examining the gonad maturity of 100 specimens
displaying the full range of color and pattern variability. The results, he believes, showed clear correlation between the color and pattern
gradient and the level of gonad maturity.
"In simple terms, the more "Açu-like" a specimen (shown on the right), the closer it was to
spawning condition, and the more "Paca-like" a specimen, the less ready it was to spawn,"
says Reiss. "This provides clear evidence that the color and pattern variants are simply
peacocks changing their clothes. Just like us, they put on their finest outfit when it's time to meet the other sex."
Editor's Note: Tips reprinted with permission from PBA's "The World of Peacock Bass" monthly
eZine.
|
