General Articles Right Arrow About Right Arrow Glossary • Article © Amanda Parker, uploaded July 26, 2010

Acidity The amount of acid present in a solution, often expressed in terms of pH. More...
Acidosis Low pH in the blood of a fish (or other animal). May be caused by a sudden drop in aquarium pH
(see pH Crash). Can be fatal.
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Acoustic Relating to the sense of sound and/or vibration. More...
Adhesive Spawner A species that lays eggs that stick to a surface. More...
Adipose Fin A fin on the dorsal surface located between the dorsal fin and the caudal fin. The adipose fin is
composed of fatty tissue and (rarely) a leading hard ray or a few soft rays as seen in some
catfishes such as most Callichthyidae, Loricariidae and Sisor (the Indian Whiptail catfish Sisoridae).
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Adult A fish capable of reproducing successfully. More...
Aeration The process of passing air through water to exchange gasses. In an aquarium, this may be done with
an airpump and airstone or a powerhead.
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Aerobic Life requiring free oxygen. More...
aff. Literally means "affinis." An animal appears related but is different. More...
Agressive mimicry A form of similarity in which a preadator gains an advantage by taking a resemblance to its prey or a resemblance to a species which its prey does not find a threat. eg.some lepidophage(scale eating)fish do this to get close to their prey. More...
Alarm Substance Also called Schreckstoff. A compound unique to a group of fishes known as the Ostariophysi (which includes Catfishes).
When the skin of an Ostariophysan is damaged, special cells rupture and release Alarm Substance, warning
other members of the shoal of imminent danger.
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Albino An animal lacking pigmentation causing the animal to appear white. A true albino has red eyes. More...
Alimentary Canal The complete digestive tract from mouth to anus. More...
Alkalosis High pH in the blood of a fish (or other animal). Generally caused by a sudden move from water of
low pH to high pH without an acclimitization process.
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Allele Alternative forms of genes. Example: For the gene controlling pigmentation, there are two forms: normally
pigmented and albino. Also see gene.
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Amelanism An animal lacking black pigment. Yellow and red pigments are present. This animal is not
a "true" Albino. Also see Leucism and Xanthism.
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Ammonia NH3/NH4 ions. Ammonia is the first stage of the breakdown of fish waste, food and plant matter in
water. The odor is very strong and distinctive. Can be converted to nitrite by "good bacteria." See also Nitrogen cycle.
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Anadromous Fish who spend their lives in the ocean and migrate to freshwater when it is time to spawn. More...
Anaerobic Life that does not require free oxygen. More...
Analagous A structure that resembles another structure in function, but not in form. More...
Anastamosis The joining of multiple structures into a single network. May apply to anatomy (blood vessels) and
geography (rivers). Plural: Anastamoses.
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Anoxia A lack of free oxygen. More...
Anterior Toward the front. More...
Anthropogenic Relating to the impact(usually negative) of humans on an environment. More...
Anthropomorphic Giving human attributes to animals. Example: Bugs Bunny is able to walk like a human being. This is
the Anthropomorphization of an animal.
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Aquarium An enclosure, such as a glass tank, outfitted with lifesupport equipment for the purpose of
keeping underwater animals and plants alive.
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Armoured A fish having a protective outer covering such as Scutes, Bony Plates and/or Scales. More...
Aufwuchs Literally meaning "growth" in German. Non-burrowing organisms that grow on the substrate
forming a coating of detritus.
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Axanthic An animal lacking yellow pigmentation. The animal will be entirely black. More...
Axillary From the latin axilla meaning armpit or underarm More...
Backwater A quiet pool off of a stream. More...
Barbels Threadlike projections that extend from the corners of the mouth or beneath the chin
of catfish. Sometimes called "whiskers." Barbels are covered with taste buds.
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Batesian mimicry Similar bright colors or patterns being used as a warning system between unrelated animals but one or more may not be noxious animals. More...
Benthic Living at the bottom of a lake, river or ocean. More...
Benthopelagic Capable of living near the bottom, middle and/or upper levels of a lake, river or ocean. More...
Bifurcated Forked or divided in two parts. Some catfishes have a Bifurcated caudal fin. More...
Biodiversity The sum total of all living things in an ecosystem. More...
Biofilm A mix of microorganisms whose cells are adhered to each other on surfaces of the aquarium. More...
Bioload The demand on lifesupport systems created by aquarium occupants. The more fish there are in an aquarium,
the greater the Bioload.
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Bioregion A geographical area described in terms of its unique combination of plants, animals, geology, climate and water features, an area defined by natural boundaries and distinct living communities rather than artificial borders. Sometimes called an Ecoregion. More...
Biotope A portion of an ecosystem with specific conditions and life forms. An aquarium may be set
up to reflect a specific Biotope, such as a river from a particular region.
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Blackwater A type of soft, tropical water that supports unique plants and animals. Blackwater occurs when tannic acids from
nearby vegetation seep into the water. In an aquarium, bogwood and additives may help acheive this effect.
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Bogwood Waterlogged wood used for the aquarium. More safely bought at an aquatic retailer, but
can be collected from rivers or lakes. Will often leach tannic acid into the aquarium water which
can be desirable for certain species, but makes the water appear "tea like."
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Brackish Water that has some salt added. This occurs in nature, for example in tidal estuaries More...
Branchial Of the gills. More...
Breeding The measures required for a male and female from a certain species to produce offspring. More...
Brine Shrimp Artemia salina. A common fish food. More...
Brood A group of offspring that arises from a clutch of eggs. More...
Bubblenest A nest for females to lay eggs in, built by one or both parents, from secretions and air. More...
Buccal Of the mouth and/or cheeks. More...
Buoyancy The ability to float. More...
Bycatch The accidental capture of species "X" during the targeted capture of species "Y." More...
Carnivore A species which will primarily eat meat based foods. More...
Casque Helmet-shaped. More...
Catadromous Fish who spend their lives in freshwater and migrate to the ocean when it is time to spawn. More...
Caudal Of the tail. More...
Caudal Fin The tail fin. More...
Caudal Peduncle The base of the tail which acts as a "wrist." More...
Cave Spawner A species that lays eggs in a cave. More...
cf. Literally means "confer." An animal appears similar to an identified species, but without certainty or confirmation. More...
Channel The main part of a river. More...
Chelation A chemical method of binding metals such as iron for use in plant fertilization. More...
Chloramine A chemical compound commonly added to the domestic water supply as a disinfectant. Chloramine
is a combination of ammonia and clorine and is more potent than chlorine alone.
Many dechlorinators will also remove Chloramine(make sure to check the label).
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Chlorine A chemical commonly added to the domestic water supply as a disinfectant. Chlorine acts as an irritant on
fish and also kills "good bacteria." Aerate the water for 24 hours or use a dechlorinating agent to remove
it from the water.
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CITES An abbreviation for Convention on International Trade in Endangered Species of Wild Flora and Fauna.
An agreement among governments to restrict trade in species that are endangered and threatened.
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CLOFFSCA "Checklist of Freshwater Fish in South and Central America." A book listing the species found in
freshwater in South and Central America, with brief reference to original description, synonyms, distribution
and maximum size. The data in this book can also be found in Fishbase.
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Clutch A group of eggs laid in the same place at the same time. Many catfishes lay their eggs in clutches. More...
COF Catalog of Fishes. A list of all species of fish which can be found on-line here. More...
Commercial Extinction A food fish no longer common enough to be profitable. More...
Common Name The vernacular name for a species. Common Names may vary by location and/or language and often cause confusion.
Different species can have the same Common Name and one species can have several Common Names.
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Community Fish Fish that will live with other species of fish and not cause either
themselves or their tankmates any trouble. Also can imply the fish will adapt to a
broad range of water conditions, although this should not be assumed.
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Compatibility The ability of a species to live with others. More...
Compressed Flattened from side to side. More...
Concave Curved inward. More...
Condition To prepare fish for spawning. Example: by feeding particularly nutritious foods. More...
Conductivity Literally, the measure of electricity through water. For aquarists, this translates into a measurement of which ions
such as calcium, hydrogen, sodium, etc. may be present in the water. A very high level of Conductivity could
indicate either polluted water or water with too many additives(i.e. plant fertilizers or food). Water with
very low Conductivity may be achieved through reverse osmosis filtration, deionization or distillation.
Conductivity is measured by electronic meter, using units called microSeimens. Similar to TDS.
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Congener One or more species belonging to the same genus. More...
Consanguinity Relationship by blood or by a common ancestor. (from the Latin consanguinitas) More...
Conspecific Belonging to the same species. More...
Contaminant A fishkeeping term in which species "X" in found in a shipment of species "Y." This could be due to Bycatch, or
deliberate/accidental mixing by the fisherman/exporters/importers.
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Convex Curved outward. More...
Cool Links Offramps of interest on the information superhighway. More...
Coprophagy Coprophagy refers to many kinds of feces eating, including eating feces of other species (heterospecifics), of other individuals (allocoprophagy), or its own (autocoprophagy) ??? those once deposited or taken directly from the anus. More...
Cordiform heart-shaped More...
Courtship Ritualistic behaviors that occur prior to spawning. More...
Crepuscular A species which is normally active in the half light of dusk and dawn. More...
Crustaceans A mainly aquatic group of animals that has a hard outer skeleton for protection. Included in
this group are shrimp, lobster, crab and barnacles.
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Cyanobacteria Small and usually unicellular bacteria that are aquatic and photosynthetic. Distinction of having the oldest known fossil records. More...
Cyclops A type of copepod rangeing in size from 1-3 mm., often used live or frozen as fish food. Called a Cyclops because of the single eye spot. More...
Daphnia A type of water flea which is used as a fish food. More...
Deionization A process where water is filtered through ion-exchange resins. More...
Dentition The arrangement of teeth. More...
Depressed Flattened from top to bottom. More...
Detritus Also called mulm. Uneaten food, dead plant matter and faeces which accumulates at the bottom of
a fish tank. Detritus is full of nutrients and promotes the growth of unwanted algae.
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Dimorphic Having two or more forms. Often, male and female catfish of the same species are quite distinct in appearance.
Such species are said to be sexually dimorphic.
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Distal Away from a point of reference, usually the center of the body. Opposite: proximal. More...
Distilled Water Water with nothing in it except dissolved gasses. This is the purest type of filtered water. More...
Distribution An indication of how widespread or abundant a species is. More...
Dither Fish A fish or group of fish added to a tank that help other tank occupants feel safe and come out of hiding. More...
Diurnal Happening during the day, or daily. More...
Dorsal Of the back. More...
Dorsum With fish this refers to the upper side of the head or body. More...
Earthworm Common Earthworms are sometimes used as a fish food. More...
Ecoregion A geographical area described in terms of its unique combination of plants, animals, geology, climate and water features, an area defined by natural boundaries and distinct living communities rather than artificial borders. Sometimes called a Bioregion. More...
Ectotherm A species whose body temperature is determined by its surroundings, i.e. "cold-blooded." More...
Electrogenic Organ An organ present in some fishes that generates an electrical current to locate food and/or prey. More...
Electroreceptive Organ An organ present in some fishes that allows for "listening" to electrical signals. More...
Emarginate Slightly indented. More...
Endangered Species An animal or plant that is very close to extinction. More...
Endemic A species restricted or contained in a specific area. More...
Epibenthic Living on the surface of the bottom in a body of water. More...
Epiphytic Plants (bolbitis, Anubias, Java Fern, etc.) that are not inserted in a substrate but are attached to surfaces. More...
Erectile Used to describe spines that can be raised and often locked into place. More...
Estuary A type of ecosystem that occurs when a river runs into the ocean. An Estuary will have variable
saline levels.
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Etymology The origin or meaning of a word. More...
Euryhaline Life capable of tolerating a wide range of salinities. More...
Euthanasia The practice of ending a life in a manner which relieves pain and suffering. More...
Evaporation Conversion from a liquid state to a gaseous state. More...
Evaporative Concentration The process where dissolved substances become stronger when water evaporates. Example: Between
water changes in an aquarium, water will evaporate causing waste products (nitrites, nitrates, etc.)
to become more intense. This is called Evaporative Concentration.
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Evertible The ability to turn inside-out. More...
Evolution The historical development of species, in which genetic traits may be transferred over generations via
natural selection.
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F0 An original set of parents in a breeding program. May also refer to a wild-caught fish kept in captivity. More...
F1 The first filial generation. May also refer to the first children of a particular set of wild-caught parents (F0).
All children of the F0 parents will be considered F1.
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F2 The second filial generation. May also refer to the "grandchildren" of a particular set of wild-caught parents (F0).
All "grandchildren" of the F0 parents will be considered F2.
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Falcate Sickle-shaped, curved and tapering to a point. More...
Family A taxonomic grouping between Order and Genus. A group of related Genera. More...
Fecund A species with a high reproductive rate. More...
Fecundity The potential rate of reproduction of a species. More...
Feeding Advice on what this species eats. See Carnivore,Limnivore and Omnivore. More...
Fertilization The process where a female reproductive cell and a male reproductive cell successfully join to form offspring. More...
Filamentous Having thin, thread-like projections. More...
Filter Any device that maintains water quality. The common types are power (or hang-on-back),
canister and internal. For more information, see this article.
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Finfold A "full-body" fin in a larval fish that will develop into the the dorsal, caudal and anal fins of an adult fish. More...
FishBase Universal computerized databases of fishes available here. More...
Fishless cycling Cycling is the procedure where an aquarium, and in particular it's filtration system, builds up "beneficial/good bacteria". The fishless part refers to using a source of ammonia other than fish, to avoid the fish being exposed to ammonia and nitrite levels unnecessarily. See also Nitrogen cycle. More...
Flashing When a fish "scratches" on objects in the aquarium. This may be due to an irritation, such as an external parasite. More...
Fluviatile Existing in or about rivers or streams. More...
Fork Length abbr. FL The distance from the tip of the snout to the fork of the tail. More...
Fractional Spawner Eggs are released a few at a time over a number of days as opposed to all at once. More...
Freshwater Characterized by having low concentrations of dissolved salts and other total dissolved solids as opposed to seawater and brackish water. Also sometimes called "sweet water". More...
Fry Another term for a larvae or juvenile fish. More...
Furniture The way to decorate a tank. Also see Bogwood and Substrate. More...
Fusiform Tapered on both ends. Cigar-shaped. More...
Gene A region of DNA that determines a trait of an organism. There are two copies of each gene in an organism.
One is inherited from the mother. The other is inherited from the father. Also see allele.
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Genera Plural of Genus. More...
General Remarks Notes of interest on a species. More...
Genital Papilla In some fishes, a tube extending from the genital pore, behind the anus. More...
Genus A taxonomic grouping between Family and Species. A group of related Species. More...
Gestation The time between fertilization and hatching. More...
GFCI An abbreviation for "Ground Fault Circuit Interrupter." A type of electrical outlet that opens the circuit when
excess amperage is detected. A safety device more commonly used in the United States and installed in
individual electrical outlets. Also see RCD.
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GH An abbreviation for Gesamthärte, literally meaning "Total Hardness" in German. A laboratory standard for
measuring the concentration of calcium and magnesium ions in water.
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Gills Respiratory organs of fish. More...
Gland An organ in the body that synthesizes a substance. More...
Gonads Reproductive organs. Ovaries in females. Testes in males. More...
Gonopodium The modified anal fin of a Livebearer male used to deliver sperm to the female's vent. More...
GPD Gallons per day. More...
Gravid Referring to a female full with eggs. More...
Grazing Method of feeding in which a fish feeds on the biofilm which grows on surfaces in the water. More...
Green water Suspended microscopic algae giving an overall green appearance to a container of water. More...
Gustatory Relating to the sense of taste. More...
Habitat Where a species lives. More...
Hardness The amount of calcium and magnesium ions in water. May be measured in ppm (parts per million)
or mg/l (milligrams per liter). Hard water has more than 200 ppm. Soft water has less than 100 ppm.
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Head Length Abbr. HL. The distance from the tip of the snout to the end of the operculum. More...
Herbivore A species which will primarily eat vegetable based foods. Herbivores may also eat small amounts of meat based food. More...
Heterospecific From a different species. More...
Hierarchy Social structure within a group of fishes. More...
Hits A simple counter of how often a particular data sheet, image or article has been viewed. More...
Holotype The single specimen (or part of a specimen in the case of fossil taxa) designated
as the name-bearing type of the species.
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Homologous A structure that resembles another structure in form, but not in function. More...
Hospital Tank Also called a Quarantine Tank. A tank set up to hold fish that need medical treatment and/or isolation. More...
Husbandry Seeing to the overall care and welfare of an animal. More...
Hyaline In ichthyology the term usage denotes a type of colorless, transparent substance. More...
Hybrid Offspring who have two distinctly different species as parents. More...
Hybridogenesis It occurs in some animals that are hybrids between species. More...
Hydra A genus of simple fresh-water, predatory animals possessing radial symmetry belonging to the phylum Cnidaria and the class Hydrozoa. More...
Hyperoxia The actual oxygen concentration is higher than the oxygen concentration of water fully equilibrated with air. More...
Hypogean Living or occurring under the earth's surface. More...
Hypoxia The actual oxygen concentration is lower than the oxygen concentration of water fully equilibrated with air. More...
Ichthyology The scientific study of fishes. More...
Ichthyotoxic Poisonous to fish. More...
ICZN An abbreviation for "International Commission on Zoological Nomenclature." The governing body that sets the
standards for naming plants and animals. The standards may be found here.
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Identification What to look for when trying to find out what type of species you are looking at. More...
Immunity The ability of an organism to overcome a pathogen. More...
Inbreeding When close relatives mate. Examples: A mother with a son. A father with a daughter. A brother with a sister.
This is generally considered bad breeding practice as it reduces genetic variability and increases the risk of
deformities. Inbreeding may be used to create specific traits, such as long fins or color morphs (albinos).
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Indigenous Native, but not endemic. Also see Native and Endemic. More...
Inferior Directed downward. In Icthyology, also refers to a mouth directed downward. More...
Infusoria Miscellaneous microorganisms found in detritus. When properly cultured, Infusoria make an excellent fry food. More...
Inorganic A chemical compound which is not carbon-hydrogen based. More...
Insectivore Species that eats insects as its main diet. More...
Interopercle One of a series of bones which makes up the Operculum. More...
Introduced Describing a species that humans have released into a particular area. More...
Invasive An introduced species of plant or animal that causes damage to an ecosystem. More...
Invertebrate An animal without a backbone. More...
IUCN International Union for Conservation of Nature. An organisation started in 1948 to support and coordinate conservation efforts all over the world. In particular, they publish a list of species showing how endangered they are in the IUCN Red List. More...
IUCN Red List A list from IUCN of species and their status from a conservation perspective, ranging from Least Concern to Extinct. The list is searchable on http://www.iucnredlist.org/.
The IUCN red list is the basis for the CITES trading restrictions.
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Junior Synonym The later established of two synonyms. A Senior Synonym has priority over a Junior Synonym. More...
Juvenile The post-larval stage of a fish where much differentiation and change occurs. More...
Keel A narrow, hard ridge. More...
KH An abbreviation for Karbonathärte, literally meaning "Carbonate Hardness" in German. A laboratory standard for
measuring the concentration of calcium and magnesium carbonates in water.
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Krill The common name given to the order Euphausiacea of shrimp-like marine crustaceans and available frozen as aquarium fish food. More...
Labyrinth Organ Also called Accessory Breathing Organ. A lung-like apparatus found in certain fishes which allows them to breath air. More...
Lacustrine Of lakes. More...
Larva The state a fish after it has hatched but before it is free-swimming. More...
Lateral Of the side(s). More...
Lateral Line A sensory canal (which branches into pores) that runs through the body of a fish. The lateral line
can vary in length depending on the species. The lateral line is very important in detecting changes in pressure.
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Lectotype A name-bearing type designated from a syntype series. This is done if the syntypes
consist of more than one species and the identity of the species in question needs
to be fixed. A lectotype has the same status as a holotype/neotype. The rest of the syntype series
become paralectotypes and have no name-bearing status.
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Lentic Of still inland waters. Examples: swamps, ponds and lakes. More...
Lepidophage A specialized feeding behaviour where a fish feeds exclusively on, or at least primarily, fish scales. More...
Leucism An animal with white pigmentation, but normal eye color. This animal is not a "true" Albino.
Also see Amelanism, Axanthic and Xanthism.
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LFS Abbreviation for Local Fish Store. More...
Limnivore Literally eating "mud-based" foods. Fish that feed on Aufwuchs or biofilm. Examples of Limnivores include
Ancistrus, Baryancistrus, Chaetostoma and Hypostomus species.
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Lipbrooder A fish that "sits" on fertilized eggs with its mouth as a form of parental care. A Lipbrooder will
carry the clutch of eggs with him until they are ready to hatch. Example: Loricaria spp.
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Lotic Of running water. Examples: Rivers, streams and creeks. More...
Lunate Crescent-shaped. More...
Lutino An animal lacking black pigment. Yellow and red pigments are present. This animal has red eyes. Also see Albino , Leucism and Xanthism. More...
Mandible The lower jaw. More...
Maxilla The upper jaw. More...
Maxillary Barbels Barbels on the upper jaw. More...
Melanin Pigment (brown or black) found in skin or hair. More...
Melanism An overload of melanin causing an animal to become completely dark. More...
Mental Barbels Barbels on the chin. More...
Meristics Countable traits that can be used to describe a particular species of fish, or used to identify an unknown species. More...
Metabolic Rate The speed at which an organism converts food into energy and waste. More...
Metabolism The biochemical process in which an organism converts food into energy and waste. More...
Milt Fish sperm. More...
Mimicry The ability of a species to imitate another's behavior or appearance. Some species may imitate an inanimate
object, such as a leaf or a branch to blend in with the background and avoid predation.
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Monophyletic Having a single common ancestor. More...
Monotypic Referring to a genus or family that contains a single species. More...
Morph A variation or a different form. Example: longer fins or a different color on the same species. More...
Morphology The scientific study of the structure and form of organisms. More...
Mouthbrooder A fish that carries the eggs and sometimes the larvae in its mouth. The eggs may be carried by the female
or the male, depending on the species. Phyllonemus typus from Lake Tanganyika is uniques among catfishes in that
the parents share Mouthbrooding responsibilities. With Arius graeffei from the South Pacific, the male
can carry up to 120 eggs in his mouth for 6 to 8 weeks.
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Mucus A protective layer that functions to protect against infectious agents such as fungi, bacteria and viruses. More...
Mullerian mimicry Similar bright colors or patterns being used as a warning system between unrelated dangerous or noxious animals. More...
Mulm Fish wastes and other solid matter that accumulates in the aquarium. More...
Naked Referring to a fish without scales. More...
Nape The area on the back between the head and the dorsal fin. More...
Nasal Barbels Barbels on the nose. More...
Native Describing a species that occurs naturally in a particular area. More...
Necropsy Autopsy performed on an animal. More...
Necrosis The death of cells in a part of the body. More...
Neoteny A condition where juvenile characteristics extend into adulthood. More...
Neotype A name-bearing designation subsequent to the original description. Neotypes have the same status
as holotypes, and are designated to replace holotypes when they are lost and the identity of
the species in question is in doubt.
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Neutral Water which has a pH of 7.0 at a temperature of 20° Celsius. The point where the concentration
of an acid and an alkali are equal.
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Nitrate NO3 ions. Nitrate is the "final" stage of waste breakdown in water. It is mildly poisonous
to fish but some will survive in water with levels as high as 100 ppm,
although this is not recommended. (See Nitrogen cycle)
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Nitrite NO2 ions. Nitrite is VERY poisonous to fish since it prevents oxygen uptake, among other things. After
ammonia is broken down in the aquarium by "good bacteria," Nitrite is the byproduct(see ammonia).
Nitrite can also be broken down further by "good bacteria."
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Nitrogen cycle The process where the fish waste in form of ammonia is converted to nitrite and then nitrate. This process takes place in the filter, with the help of beneficial bacteria. More...
Nocturnal Happening during the night or nightly. More...
Nomenclature The system of scientifically naming plants and animals. More...
Nominal Taxa A taxon which is denoted by an available name. Example: Homo Sapien. More...
Nuchal Of the nape. More...
Nuchal Shield A bony plate between the back of the head and the dorsal fin. More...
Obligate Forced to do something to stay alive, i.e. obligate parasite cannot survive without a host. More...
Ocellus Colored marking on a fish that resembles an eye, plural is ocelli. More...
Odontodes Bristlelike structures on the surface of certain catfishes. More...
Offsite Resources Places other than Planet Catfish with useful information on a certain species. More...
Olfactory Relating to the sense of smell. More...
Omnivore A species which will eat both vegetable and meat based foods. More...
Ontogeny The entire sequence of events involved in the development of an individual organism. More...
Oocyte An egg cell. More...
Oophagy The eating of eggs, usually (but not necessarily) as a major portion of an animal's diet. More...
Opercular spine Spine projecting from the operculum (gill cover). More...
Operculum A bony flap located behind the head, on each side of the body, which protects the gills. More...
Organic A chemical compound which is carbon-hydrogen based. More...
Osmoregulation An organism's ability to maintain the proper balance of water and salts. More...
Osmotic Pressure The force that moves water across a semi-permeable membrane. More...
Osteology The study of the structure and development of bones. More...
Ostracoda A class of small crustaceans usually less than 1 millimeter in length. Also called seed shrimp. More...
Other Parameters Also see General Remarks. May include water hardness, conductivity, water movement, seasonal variations and
water specific husbandry difficulties.
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Otophysans This group comprises much of the world's Freshwater fish diversity and includes carps, loaches,
characins, electric (knife) fishes and catfishes. Also see Weberian Apparatus.
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Outcrossing Adding new blood from an unrelated source. Outcrossing is used in conjunction with other inbreeding practices to
to try to reduce the problems associated with less genetic diversity.
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Oviparous A fish which lays eggs that are fertilized, develop and hatch outside the body. More...
Oxbow A "U"-shaped lake that occurs when a section of river, stream or tributary is cut
off from the main section and isolated. Also applies to a type of river that
has many "U"-shaped meanders in its course.
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Paedomorphism The retention of juvenile characteristics into adulthood More...
Paired Fins A term used to indicate the fins that come in pairs on a fish, i.e. the pectoral and ventral fins. More...
Parasite Organism that is living in another with no benefit to its host and is dependant on this host for survival. More...
Paratype Additional specimens used in the original description of a species. Strictly speaking, a paratype has
no name-bearing status (and is no different from any other specimen of that species).
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Parthenogenetic A fish that reproduces without fertilization, the sperm induces development of the egg but there is no exchange of genes. More...
Parturation Giving birth. More...
Pathogen Virus, bateria or other microorganism that causes disease or illness to its host. More...
Pathognomonic Characteristic or diagnostic of a specific disease. More...
Pectoral Of the chest. More...
Pectoral Girdle A set of bones which supports the pectoral fin. More...
Pelagic Living at the middle and/or upper levels or a lake, river or ocean. More...
Pelvic Of the pelvis or hip area. More...
Periphyton Microscopic plants and animals which attach and grow on substrate. Also see Aufwuchs. More...
pH Literally pondus Hydrogeni. The measure of a liquid's acidity or alkalinity. pH is measured from 0.0 (very acidic) to 14.0
(very alkaline) with 7.0 being neutral. This measurement is logarithmic, meaning any change is significant. A sudden
change in pH will cause a great deal of stress, or may even lead to the death of a fish.
More...
pH Crash Rapid lowering of pH in an aquarium due to lack of buffering capacity (see Hardness). More...
Phenotype The charactaristics of an organism based on genetic inheritance. Examples: In humans, eye-colour (blue or brown).
In fish, long fins or short fins.
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Photoperiod The amount of light in a day, either natural or artificial. More...
Phototaxis The movement of an organism or a cell toward or away from a source of light. More...
Pigmentation The substance that gives a plant or animal its color. More...
Pinnate Feather-like. More...
Piscivore A species which eats exclusively or, at least primarily, fish. More...
Planaria A flatworm that often sets up residence in an aquarium and is considered a nuisance. More...
Pore An anatomical structure-a very small opening on the surface of the skin More...
Posterior Toward the rear. More...
Potamodromous Fish who migrate completely in freshwater to spawn. More...
PPB Parts Per Billion. More...
PPM Parts Per Million. More...
PPT Parts Per Thousand. More...
Predator An animal that survives by capturing and eating other animals. More...
Pronunciation The correct way to say a word. More...
Protrusible A mouth that can be extended. Some catfishes have a Protrusible mouth to catch prey. More...
Proximal Toward a point of reference, usually the center of the body. Opposite: distal. More...
Psammophile A sand-loving organism More...
Psammophilous The ability to inhabit sandy areas. More...
Quarantine Compulsory isolation, typically to contain the spread of something considered dangerous. More...
Ray A rod-like support structure for the fin. More...
RCD Residual Current Device, a device that protects humans from current by isolating (breaking) the circuit, when there is a fault in the electrical circuit. See also GFCI. More...
Reference Where the original description of the species was published. With this, a (scientific/university) library can find the
original discription. May also contain further reading on points raised in the page.
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Registered Keeper The "My Cats" registered keeper facility allows members of the forum to register that they own a particular species, and record how they are keeping the fish. More...
Respiration Process of passing gaseous nutrients to the blood. More...
Reticulate Forming a mesh-like pattern. More...
Reverse Osmosis Also called RO Filtration. A method of filtration where the water is forced across a semi-permeable
membrane. The most common type of membrane is made of Thin Composite Film (TFC). This
method is between 94-99% effective in laboratory conditions. Cellulose Tri-Acetate (CTA) membranes are less
effective and less common. Low water pressure and exceedingly poor water quality will reduce the
lifespan of an RO membrane. The typical layout of a filter is a 1 or 5 micron pre-filter, followed
by a carbon block pre-filter and then the RO membrane.
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Revision (Taxonomy) To re-examine a species, genus or family to correct mistakes/inconsistancies and possibly
make changes to the status of described taxa.
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Rheophilic Species that love moving water. More...
Rheotaxis Response of an organism to face towards or sometimes away from a current of water. More...
Rictal Barbels Barbels extending from the corner of the mouth. More...
Rictus The corner of the mouth. More...
Riffle A rocky part of a stream with fast-moving water. More...
Rift Lake A lake formed by volcanic activity which produces a split in the landscape. Over time, this
is then filled by rainwater and/or rivers producing a lake. Fish from Rift Lakes
Tanganyika, Malawi and Victoria in Africa are commonly imported.
More...
Riverine Of rivers. More...
Rostrum Snout. More...
Rugose Rough or wrinkled. More...
Saddle A patch of color that starts at the midline of the body and extends down the sides. More...
Salinity A measure of dissolved salts in water. More...
School Generally the same as schoal, but it is sometimes used to mean a closer shoal where all the fish have
the same orientation. Example: the fish forming patterns in the Disney/Pixar feature film Finding Nemo.
Also more often associated with Marine fish rather than Freshwater varieties.
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Scientific Name Latin-based nomenclature used by scientists to identify a species. A species may only have one
Scientific Name to eliminate confusion.
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Scutes Bony plates on the surface of the skin. Unlike scales, scutes cannot be easily removed from the skin. More...
Seine A net used to encircle fish. More...
Semilunar Half-moon shaped. Also see Lunate. More...
Senior Synonym The earlier established of two or more synonyms. A Senior Synonym has priority over a Junior Synonym. More...
Serrae A row of small spines or recurved points along the pectoral or dorsal spine. More...
Sessile To be attached at the base. Also, a fish that is sedentary. More...
Sexing How to differentiate a male from a female of a certain species. More...
Shoal A group of fish, usually all of the same species, that swim together as a group. More...
Size The maximum length of a fish in SL. See Standard Length and Total Length. More...
Snout The nose area. Also see Rostrum. More...
sp. Abbreviation of Species in singular form (so only one species). More...
Spawning Eggs and sperm released or deposited, usually into water, by aquatic animals. More...
Species Basic unit of classification in taxonomy. One or more species that are considered to have the same evolutionary ancestor are grouped in the same Genus. More...
Speciose Usually referring to a family or genus that has a large number of species. More...
Spine A hard ray. More...
Spinelet A locking mechanism found at the base of the Dorsal Spine. It holds the Dorsal Fin erect. More...
spp. Plural of sp.
Example: There are more than one dozen described Panaque spp.
More...
Standard Length Abbr. SL The distance from the tip of the snout to the base of the tail. To put it another way, the length of the fish excluding the caudal fin. More...
Strip The removal of eggs and sperm for artificial breeding also to remove eggs or young from the buccal cavity of mouthbrooding fish. More...
Sub-Adult A young fish similar in appearance to an adult, but not yet capable of reproducing. More...
Subcutaneous Beneath the skin. More...
Substrate Material used to cover the aquarium floor. Examples: gravel or sand. More...
Subterminal A mouth position between inferior and terminal. A lot of catfishes have Subterminal mouths. More...
Superior Directed upwards. In Icthyology, also refers to a mouth that is directed upwards. More...
Supraoccipital The median bone at the upper end of the cranium. More...
Symbiotic A mutually beneficial relationship between two different organisms. More...
Synonym In general, another name for the same thing. In zoology, each of two (or more) different names for
the same taxon or taxonomic entity.
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Syntype Multiple specimens designated as name-bearing types. Each syntype has equal status as a name-bearing
type as its fellow syntypes.
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T-Position The manner in which some Corydoradine catfishes breed. So named because the breeding pair look as if
they are forming the letter "T." Also see More...
Tankbuster A fish that grows too large for the average home aquarium. More...
Tautonomy A taxonomic designation, such as Hara hara, in which the genus and species names are the same, commonly used in zoology but no longer in botany. More...
Taxon A group or groups of populations that are related. A Taxon has charactaristics which separate it from
other populations. Plural: Taxa
More...
Taxonomy The theory and practice of classifying organisms. More...
TDS Total Dissolved Solids. A way to calculate water quality by measuring organic and inorganic
substances present. Total Dissolved Solids may be measured in the laboratory or, more
conveniently, by electronic meter, using mg/l(milligrams per liter). Similar to Conductivity.
More...
Teleost A bony fish. More...
Temperature The range of warmth a species can tolerate, noted in both degrees Celsius and Fahrenheit. More...
Terminal Literally an end. In Icthyology, also refers to a mouth directed forwards, i.e. at the tip of the Snout (rostrum). More...
Topotype Specimens collected from the type locality (where the holotype/syntypes were collected) subsequent to
the original description. Topotypes have no name-bearing status (although they are useful as potential neotypes
should the holotype be lost.)
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Total Length Abbr. TL The distance from the tip of the snout to the tip of the tail. More...
Toxin Poisonous substance produced by living cells or organisms. More...
Troglobitic A reference to any creature having a cave-dwelling mode of life. More...
Troglomorphic Morphological characters that are adaptions to living in the constant darkness of caves. More...
Trophic Level A stage in the food chain a species occupies. Example: A big fish eats the small fish, which in turn
eats an even smaller fish.
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Truncate With a straight edge; square cut. More...
Tubercules Small skin growths that appear on the head and sometimes body of sexually mature fish,
normally the male.
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Tubifex Tubificid worms may be used as fish food. They may be fed freeze-dried, frozen or live.
Care must be taken when feeding live Tubifex Worms as they are notorious for carrying disease. If too many are
released into the aquarium, they will establish themselves in the substrate and detrimentally impact water quality.
More...
Turbid Water clouded by suspended particulate matter. More...
Type Locality The place where the Holotype specimen used to describe a species was found. More...
Ventral Of the underside. More...
Ventral Fin Basket A clamping of the ventral fins by the female of some Corydoradine catfishes so that she may carry
fertilized eggs. Also see T-Position.
More...
Vermiculation A wavy, worm-like or network pattern. More...
Villiform Teeth Fine, long teeth that are crowded together. This gives the appearance of a patch of velvet. More...
Vomer The bone on the palate, i.e. the "roof of the mouth." More...
Weberian Apparatus The modified first four or five vertebrae that connect the dorsal wall of the swimbladder
to the inner ear. This increases sensitivity to sound. The Weberian Apparatus is present in a
group called Otophysi.
More...
Xanthism An animal which is yellow or golden in color. This may happen in nature or through selective breeding. More...
Xylophagy A term used in ecology to describe the habits of an herbivorous animal whose diet consists primarily (often solely) of wood. More...
Yolk Sac A pouch containing nutrients for a newly hatched larva. More...
Zoonosis A disease which can be transmitted from an animal to a human. More...

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