Description
Most species are slender, pencil-shaped fish ranging in size from under 1" to approximately 2" in length. N. marginatus, N. rubrocaudatus and N. mortenthaleri possess a shortened, blockier outline reminiscent of pencil stubs. All but one species, Nannostomus espei, possess one to five horizontal black or brown stripes with gold or silver iridescence appearing dorsal to the primary stripe. Most also display red, orange or maroon highlights in their fins, and many have flashes of these colors on their flanks as well. The recently described species, N. mortenthaleri and N. rubrocaudatus, are especially vividly colored. For N. espei alone, horizontal stripes are only weakly present and
are supplanted by five dark comma-shaped blotches. This pattern is assumed by other species at night, but only N. espei displays the pattern permanently and in daylight. The adipose fin is present in some species and absent in others, while in certain species, Nannostomus eques for example, it may be present or absent within the species. All swim in a horizontal attitude except Nannostomus unifasciatus and Nannostomus eques, which assume an oblique, 'snout-up' posture. There is a range of sexual dimorphism in the genus, it being clearly evident in several species with males being more brilliantly colored, especially with regard to color present in the fins, and far less evident in other species. However, a reliable indicator of gender for most of the species rests in the anal fin of adult males which is enlarged and elongated (as in N. espei, N. eques et al.) and/or the anal fin of males is more colorful (as in N. harrisoni, N. marginatus et al.). The popular aquarium species, Nannostomus trifasciatus, is an exception in this regard.
Read more about this topic: Pencil Fish
Famous quotes containing the word description:
“Everything to which we concede existence is a posit from the standpoint of a description of the theory-building process, and simultaneously real from the standpoint of the theory that is being built. Nor let us look down on the standpoint of the theory as make-believe; for we can never do better than occupy the standpoint of some theory or other, the best we can muster at the time.”
—Willard Van Orman Quine (b. 1908)
“The great object in life is Sensation—to feel that we exist, even though in pain; it is this “craving void” which drives us to gaming, to battle, to travel, to intemperate but keenly felt pursuits of every description whose principal attraction is the agitation inseparable from their accomplishment.”
—George Gordon Noel Byron (1788–1824)
“As they are not seen on their way down the streams, it is thought by fishermen that they never return, but waste away and die, clinging to rocks and stumps of trees for an indefinite period; a tragic feature in the scenery of the river bottoms worthy to be remembered with Shakespeare’s description of the sea-floor.”
—Henry David Thoreau (1817–1862)