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)
“I was here first introduced to Joe.... He was a good-looking Indian, twenty-four years old, apparently of unmixed blood, short and stout, with a broad face and reddish complexion, and eyes, methinks, narrower and more turned up at the outer corners than ours, answering to the description of his race. Besides his underclothing, he wore a red flannel shirt, woolen pants, and a black Kossuth hat, the ordinary dress of the lumberman, and, to a considerable extent, of the Penobscot Indian.”
—Henry David Thoreau (1817–1862)
“It is possible—indeed possible even according to the old conception of logic—to give in advance a description of all ‘true’ logical propositions. Hence there can never be surprises in logic.”
—Ludwig Wittgenstein (1889–1951)