| Nandus |
type genus of the Family Nandidae, predatory freshwater
fish of Southeast Asia |
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| Nannostomus |
pencilfish, South American characins that do best in soft, acid
water with a lot of plants and a diet of planktonlike foods |
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| Nanochromis |
small, beautiful cichlids of the Aaire River and its tributaries,
suitable for a planted community tank |
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| Narcine |
electric rays, marine elasmobranchs able to generate an electric
shock of about 20 volts; they are exhibited in specialized aquariums |
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| Naso |
large acanthurid fish of the Indo-Pacific; the males often develop
a protuberance from the center of the forehead; they are suitable
only for large aquariums, but regularly imported |
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| Nauplius |
the first instar, or larval stage, of a crustacean such as the
brine shrimp, Artemia salina |
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| Necropsy |
dissection of a dead animal specimen, usually to determine the cause
of death |
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| Necrosis |
death and detrioration of the tissues of a living organism as a
result of desease or injury |
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| Nemateleotris |
fire dart gobies, Family Gobidae, popular with marine aquarium enthusiasts
because of their bright coloration and propensity to hover motionless
in midwater; they feed on a variety of planktonic organisms |
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| Nenatobrycon |
emperor tetras, characins from western Columbia that do well in
planted aquariums |
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| Nematocyst |
a subcellular structure consisting of a projectile, ejected upon
stimulation by external contact, employed for prey capture and defense,
and found only in cnidarians |
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| Nematode |
roundworm, any member of Phylum Nematoda; certain species are important
in the aquarium either as parasites of fish and invertebrates or as
an organism cultivated for feeding to certain fish |
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| Nemenzophyllia |
a stony coral in which the individual polyps are disklike about
an inch in diameter, and arrayed along the top edge of a wall-like
skeletal structure; often displayed in minireef aquariums |
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| Nemertean |
ribbon worms, Phylum Nemertea, marine and rarely terrestrial invertebrates
with an elongate, flattened body and a proboscis retractible into
a sheath on the anterior end; colorful species are sometimes introduced
into the aquarium living within a rock cavity |
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| Neocirrhites |
one of several genera of hawkfish, Family Cirrhitidae, including
the popular flame hawkfish, N. armatus |
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| Neolamprologus |
one of many cichlid genera of the African rift lakes |
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| Neolebias |
small African characins with distinctive color differences between
the sexes; suitable for soft, acid water in planted aquariums |
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| Night coloring |
a pattern, often strikingly different from the one assumed during
daylight, adopted by some fish after sunset or during sleep |
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| Nitrate |
(NO3) the end product of the metabolism of ammonia by nitrifying
bacteria; it must be periodically removed from aquarium water to prevent
harm to the inhabitants |
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| Nitrification |
the oxidation of ammonia to nitrate by means of certain bacteria;
the process of biological filtration as it occours in the aquarium |
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| Nitrifier |
any of the bacteria capable of ammonia oxidation |
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| Nitrifying bacteria |
those prokaryotic organisms that collectively carry out nitrification,
or biological filtration |
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| Nitrite |
(NO2) a toxic anion intermediate formed in the process of ammonia
oxidation carried out in the aquarium by certain bacteria |
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| Nitrobacter |
a genus of bacteria once thought to be solely responsible for oxidation
of nitrite to nitrate during biological filtration; recent research
has shown that other genera are more likely involved |
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| Nitrofurazone |
one of several antibiotics effective in the treatment of deseases
of marine aquarium fish, although several pathogens are resistant |
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| Nitrogen |
the chemical element (n2), a gas comprising most of the atmosphere
and present in thousands of biologically important compounds |
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| Nitrogen cycle |
the natural process through which nitrogen incorporated into food
molecules by photosynthetic organisms is consumed directly or indirectly
by other organisms and subsequently excreted, acted upon by bacteria,
and made available agian for plant nutrition |
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| Nitrosomonas |
a genus of bacteria once thought to be solely responsible for oxidation
of ammonia to nitrite during biological filtration; recent reasearch
has shown that other genera are more likely involved |
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| Nocturnal |
active primarily during the hours of darkness |
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| Nonphotosynthetic |
unable to produce food from simple molecules, thus relying on food
produced by organisms with this ability |
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| Nostril |
in fish, an external opening leading to the pharynx |
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| Nothobranchius |
African killfish known as "annuals" because they hatch,
mature, and reproduce within a single season; they are popular with
specialized freshwater hobbyists |
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| Notopterus |
the clown knifefish, N. chitala, a nocturnal, predatory Asian species
that can be maintained in large aquariums if fed live foods exclusively |
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| Novaculichthyes |
dragon wrasses, Family Labridae, imported for the marine aquarium
as juveniles with striking green, white, and black coloration; adults
reach about a foot 930 cm) in length |
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| Nudibranch |
any member of the molluscan Order Nudibranchia, marine snails lacking
a shell and with the gills exposed and often retractable; often attempted
by aquarium hobbyists because of tehir brilliant coloration, they
are difficult to maintain successfully due to their specialized dietary
requirements |
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| Nuphar |
spatterdocks, members of the water lily family found along the Atlantic
coast of North AMerica and sometimes grown in large aquariums and
ponds; their flowers are not as showy as the true water lilies |
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| Nutrient |
any molecule that serves as food for a living organism |
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| Nymphaea |
true water lilies, native to North America andAsia, dwarf varieties
of which are sometimes kept in freshwater aquariums; all types are
frequently cultivated in garden ponds |
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| Nymphoides |
banana plants, small members of the water lily family in which the
roots of adventitious plantlets resemble a bunch of bananas, often
grown as a novelty in freshwater aquariums |
