Acidic: A water condition, which has a pH value lower than 7.0. A trend towards acidic water may be a sign of overfeeding.
Actinic: A type of fluorescent lighting that emits blue light. Thus, providing the proper spectra for photosynthesis. Best used for aquariums with live plants or chlorophyll containing species such as reef coral.
Activated Carbon: Solid carbon, which is used to adsorb impurities from the water - fresh or marine, and keep, it clear. It is also used to absorb and remove medicines used in the aquarium after the treatment is finished. The carbon should be changed regularly to keep it from leaching impurities back into the water.
Adipose Fin: A small fleshy fin located behind the dorsal fin and in front of the caudal fin. It is usually only found on characins.
Air Pump: An electro-mechanical pump, which is used to deliver air to the aquarium. The pump pushes air through silicon tubing and to air stones or other aquatic decor. They are also an essential for UGFs (Under Gravel Filters). An airstone is placed in each clear tube. When the air bubbles travel upward, they generate steady current, which brings water from the bottom, through the tubes and to the surface.
Air Stones: These are used with Air pumps. They increase the oxygen content of the aquarium water by disrupting the surface, to prevent a film covering, which prohibits the proper gas exchanges.
Algae: Algae are classified as plants, although they share many characteristics with monerans (fungus). It is that pesky green stuff that many hobbyists try to avoid. It may become slimy over time and will grow in fresh or marine water. They are usually produced by too much light, too much phosphate, and/or overfeeding.
Alkaline: A water condition which has a pH higher than 7.0.
Alkalinity: Sometimes called Carbonate Hardness. It is the amount of your aquarium water's ability to resist changes in pH. The alkalinity of water can be raised by using a buffer such as baking soda. Alkalinity is usually expressed in ppm (parts per million) or dH (Degree of hardness).
Ammonia: This is the first step in the nitrogen cycle. Ammonia is a by-product of fish waste and the decay of dead fish and plant material. It is perhaps the deadliest agent to tropical fish. Care must be made to ensure that the ammonia levels stay at zero.
Ammonia Tower: A biological filtration system, which consists of, a plastic chamber with a biological filtration media. Water runs through the media, which mixes with the air, and reacts with the bacteria, which serve to remove ammonia and nitrites. It is this wet / dry exchange that promotes bacterial growth. Most commonly referred to as a wet/dry filter.
Anaerobic: Living without oxygen. This is a living situation most commonly associated with "bad" bacteria.
Anal Fin: The fin, which lies beneath the body, just in front of the caudal fin.
Aerobic: Living with oxygen.
Aragonite: This composes the calcium carbonate skeletons of reef coral and some shells.
Artemia: A very common food for fresh and marine water fish. They are very tiny crustaceans that are easy to breed and maintain for long periods of time. They are a great source of food for young fry. They at a maximum grow to about 3/4 inches.
Bacteria: Small single celled organisms from the Moneran kingdom. They are known as prokaryotes, which are classified together because they lack nuclear membranes. They are the most primitive living beings, but help in the nitrogen cycle.
Ballast: The power supply for fluorescent and metal halide lighting.
Biological Filtration: A loose term, which describes the process of removing harmful compounds with bacteria. Actually, it is not filtration at all. Instead, it is the mixing of aquarium water with beneficial bacteria that transform harmful material into unharmful compounds. This process is accomplished by trickle filters (ammonia towers), UGF (undergravel filters) and various other specialty filters.
Barbel: Finger like projections most often found on the mouth of certain fish like catfish and loaches. They are used in the search for food.
Berlin Method of Filtration: A biological method of filtration, which involves only live rock and a protein skimmer.
Biological Filter: A filter, which uses bacteria to breakdown waste in the water into substances, which are less or not at all toxic.
Bio Wheel: A rotating paddle wheel type device that provides excellent wet/dry filtering.
Brackish Water: A type of water, which is between fresh and marine climates. It is usually found where large lakes or rivers flow into the ocean. The salinity leans towards freshwater.
Brine Shrimp: A very common food for fresh and marine water fish. They are very tiny crustaceans that are easy to breed and maintain for long periods of time. They are a great source of food for young fry. They grow to about 3/4 inches max. They are sometimes called as Sea Monkeys.
Brood: A family of fish, a little older than fry but not yet considered adolescent fish.
Bubble Filter: This type of filter involves a few long, plastic tubes, which remain upright in the aquarium and are attached to a plate on the bottom. In each tube is an air stone attached to an air pump. As the air bubbles rise, a current is generated which continuously brings water from the aquarium, through the substrate and to the top of the tubes.
Bubble Nest: A term used for a nest, which is suspended by a weave of tiny air bubbles. It is used as a protective coating for the eggs and the newly hatched young. It is most commonly used by the anabantids.
Buffer: A substance used to treat the water and to counteract changes in the pH value of water e.g. bleaching powder.
Caudal Fin: The caudal fin is another name for the tail.
Canister Filter: A filter, which pushes water through an external canister, which contains a filter media such as filter floss, polyester or carbon.
Carbon Dioxide: It is a molecule known as CO2, which is a byproduct of respiration. Plants require CO2 to photosynthesize, which generates molecular oxygen.
Caudal Penduncle: The long, narrow section, which leads into the caudal fin (tail).
Chemical Filtration: The process of filtering the water through a chemical substrate, most often activated carbon.
Chiller: A device used mainly in saltwater aquariums to cool the water. It is an air conditioner for water. It acts in the reverse of an aquarium heater.
Chloramine: A chemical sometimes used by municipal water treatment facilities in place of chlorine since, it is more stable in water and will not evaporate. It is easily removed with many commercially available additives. It is toxic to aquatic animals.
Chlorine: A chemical substance used by municipal water treatment facilities to eliminate bacteria from the water supply. This is toxic to fish and should be removed using either a dechlorinator or through aeration, or by letting the water stand in an open container for 24 hours. It is toxic to aquatic animals.
Cichlid: A generic term referring to a group of aggressive freshwater fish commonly found in India, South America and Africa.
Cirri: Short, stubby organs located above the eyes of some cold water species.
Deionizer: A filtration device used to purify tap water before it is introduced into the aquarium. They are normally composed of many chemical and mechanical filtration media.
Detritus: A mass of dissolved organic compounds. It is often noticeable as a layer of oily stuff or gunk that builds up in mechanical filter systems or undergravel filters.
Diatoms: Single celled protists with silica shells.
Diatom Filter: Filters, which use a diatomic filter media. Diatoms are small single celled protists, which have silica shells.
Dorsal Surface: The top part of the fish.
Dorsal Fin: The dorsal fin is the uppermost fin, located between the body and the tail.
Dosing Pump: A pump, which serves to maintain a specific water level in an aquarium. They can also be used to add a constant supply of additives or trace elements, much like a hospital IV.
Egg-Layer: A method of reproduction in which the female fish lays eggs and the male sprays them with milt (sperm.) This is the most common method of reproduction; the others are livebearers.
Egg Spots: Marks located on the rear of the body, especially on the anal fin of the male.
External Filter: A filtration device, which is kept outside of the aquarium.
Family: A scientific order of taxonomy, which contains genera, or genus.
Fry: Newly hatched or born fish.
Genus: A scientific order of taxonomy, which contains the names of species.
Gill: This is the respiratory organ used by fish. It allows dissolved oxygen to be extracted from the water in which the fish swim.
Gill Cover: A hard, bony plate, which covers the gills.
Gonopodia: A modified anal fin, which is elongated. Only appears on the males.
Gravid: A pregnant female livebearer or female who is ready to lay eggs.
Hard Water: A water condition, which has a lot of dissolved salts.
HO lighting: High Output fluorescent lighting.
Hydrogen Sulfide: A molecule composed of a hydrogen and sulfur atom. It is a toxic compound, which has a rotten egg odor. Unwanted bacteria synthesize it anaerobically.
Internal Filter: A filtration unit, which is kept inside the aquarium.
Invertebrates: Scientifically speaking, they are any animal which lacks a backbone. It is most commonly used to describe coral, but scientifically describes snails and other shelled fish.
Iodine: A diatomic molecule consisting of two iodine elements. It is needed by reef invertebrates. Protein skimming may deplete the supply, so additions are quite necessary.
Kalkwasser: A term referring to water with dissolved calcium hydroxide. It is used to add inorganic calcium to the water.
Killifish: A very beautiful group of fish, which can be quite hard to find.
Labyrinth Organ: An organ found on anabantids (labyrinth fish.) They are wrinkled areas located above the eyes, which enable them to take in oxygen from the water surface, or when on land.
Live Rock: A term used to associate the many strains of bacteria on rock which has been removed from part of a tropical reef. Live rock is essential for reef aquaria as it initiates and maintains the nitrogen cycle. It is the main element in the Berlin method of filtration.
Livebearer: A fish, which gives birth to live young.
Mechanical Filtration: Filtration, which serves to eliminate particles from the water. It is usually filters water through a substrate such as polyester, which can remove impurities as it passes through the media.
Metal Halide Lighting: Metal halide is considered by many to be a best method of lighting reef tanks. They burn much hotter than incandescent, high output (HO) and very high output (VHO) lighting. They deliver a very wide spectrum of light, which is in close association to natural light.
Mouth Brooder: Fish, which protect unhatched eggs in the mouth. Sometimes called tooth-carps.
Nitrification: This is the process in which the nitrogen cycle works. Ammonia is created by urea and decomposition. Ammonia is turned into nitrites by nitrosomonas bacteria. Nitrites are less harmful than bacteria, but still pose a threat. Nitrites are converted to nitrates by nitrobacter. Nitrates are much less toxic and are used as fertilizer for live plants. It is harmful in great quantities, however, and should be avoided in the reef tank. There are special denitrifying filters, which convert nitrates to nitrogen gas, which is explosive in high quantities.
Nitrate: Chemically speaking, it is the molecule NO3, which contains a nitrogen atom, three oxygen atoms and a lone pair of electrons. It is the last stage of the aquarium nitrogen cycle and is converted from nitrites. It is harmful to aquatic animals in high concentrations.
Nitrites: Chemically speaking, it is the hybridized molecule NO2, which contains a nitrogen atom and two oxygen atoms. It is converted from free ammonia and is harmful at any level.
Nitrobacter: A variety of air breathing bacteria, which convert nitrites to much less toxic nitrates.
Nitrogen Cycle: Ammonia is created by urea and decomposition. Ammonia is turned into nitites by nitrosomonas bacteria. Nitrites are less harmful than bacteria, but still pose a threat. Nitrites are converted to nitrates by nitrobacteria. Nitrates are much less toxic and are used as fertilizer for live plants. It is harmful in great quantities, however, and should be avoided in the reef tank. There are special denitrifying filters, which convert nitrates to nitrogen gas, which is explosive in high quantities.
Nitrosomonas: A kind of air breathing bacteria, which convert ammonia into toxic nitrite.
Nuchal Hump: An enlarged forehead on male cichlids.
Operculum: A hard, bony plate, which covers the gills.
Ozone: Ozone gas is a molecule, which consists of three oxygen molecules. It is naturally occurring in the earth's atmosphere at all levels and is essential to reef keeping. Ozone functions by sterilizing the water and relieving it of unwanted bacteria and microscopic organisms. Ozone is explosive and is harmful to fish and to humans, if in large quantities.
Peat: Peat is a moss, which is used to soften water and to decrease its pH value.
pH: The pH of water is a scientific measurement that describes how acidic or alkaline (basic) the water is. A pH of 7 is neutral. Most freshwater fish prefer a neutral pH, or a pH between 6.5 and 7.5. Cichlids generally prefer a lower pH, whereas livebearers prefer a slightly alkaline environment. Marine fish generally prefer a pH between 8.1 and 8.3.
Pectoral Fins: Fins located behind the gill covers. They are generally smaller and very delicate.
Pelvic Fins: Fins, which are located in front of the anal fin, just under the head.
Pharyngeal Teeth: Sometimes known as false teeth or characin teeth. They are teeth, which lie in the throat of some characins. In these species, there are no teeth in the mouth.
Phosphorous: An important trace element in the marine tank. Phosphorous is an element that helps composed ATP (Adenosine Tri-Phosphate), which is a building block for genetic material, specifically DNA (Deoxyribo Nucleic Acid).
Photoperiod: Refers to the number of consecutive hours that light occurs in a day. In the aquarium, it is the number of hours that the lights are kept on.
Plankton: The most minute and primitive creatures of the food chain. They are tiny organisms that drift through the layers of the ocean and serve as food for many small aquatic species.
Powerfilter: A powerfilter is a generic term used to describe any type of filtration that is powered by an electric pump.
Powerhead: A power head is a small, submersible pump, which is used to power wavemakers and UGFs (undergravel filters).
Prefilter: A prefilter is used mainly in marine tanks to remove large particles as the water leaves the tank, enroute to the sump.
Protein Skimmer: A protein skimmer is perhaps the most important piece of hardware for the salt-water tank. It is a filter used to remove organic impurities from the water. Water is sent through a fractionating column where many tiny air bubbles are pushed through it. The air bubbles generate "foam", which actually consists of organic impurities. The "foam" is channeled out of the device and is kept in a collection cup until it can be discarded. There are three main classes of skimmers.
Ray: The bones, which make up the skeleton in the fins.
Redox: This is a scientific term referring to the reduction-oxidation potential of the water. Its measurement gives an indication of how an aquarium will be able to sustain life. A high value is better than a low. The redox potential refers to an electrical charge on a molecule that has transformed in a chemical reaction. In a nutshell, it tells you how easily chemical reactions are taking place in the tank.
Reverse Osmosis: This is a purification method for tap water. Prefiltered tap water is pushed through a reverse osmosis membrane. Water that makes it through is considered pure, while water that does not, is sent through a special tube and is rendered impure. As it relies on water, which is able to pass through the membrane, it also generates a large quantity of "waste" water, which cannot be used. This is one of the best, but slowest methods of tap water purification. Reverse Osmosis units produce purified water at extremely slowly, sometimes as low as 10 or 15 gpd (gallons per day).
Reactor: This is a device used to force a controlled reaction with a given substance. The most common reactor is an ozone reactor, which forces water through a pressurized column of an air-ozone mixture.
Salt: A generic term, which scientifically refers to a cation and an anion. However, in aquatics, it refers to the proper combination of inorganic salts, composed mainly of sodium and magnesium chloride.
Scale: Small places which are scattered throughout the body of the fish. They are the primary source of protection for most fish.
Scalpel: A spine, which is located on the tail base of surgeonfish (tangs). It is retractable and gives them their name, as it looks very much like a scalpel.
Scalpel Marking: A spine, which is located on the tail base of surgeonfish (tangs). It is retractable and gives them their name, as it looks very much like a scalpel.
School: A group of fish, which swim together, usually composed of the same species or sub-species.
Scute: A type of scale most common in catfish.
Silicon: A trace element in the marine system. It is an element, which is a building block for many organisms with silica shells.
Soft Water: A water condition with very small amounts of dissolved salts.
Spawning: A term used for breeding.
Species: The most useful taxonomical name. Every living creature is assigned a unique species name, which is composed of two parts.
Specific Gravity: A scientific term, which is used to describe the salt content of water.
Strain: A variety of a certain species. The freshwater guppy, for example, has only one species name but several strains.
Strontium: A trace element, which is essential to the growth of reef coral.
Subspecies: An offset of a certain species, usually due to their separation in nature.
Substrate: Material used on the aquarium bottom. Examples include gravel, crushed coral, crushed seashells, etc.
Substratum: The many different layers of substrates found in nature or in the aquarium.
Sump: A collection container mainly used in marine tanks. As the water leaves the tank, it is delivered via gravity to a sump, which is often nothing more than a small aquarium. From there, it is pumped through the filtration system and delivered back to the aquarium.
Swim Bladder: An internal organ that helps fish maintain normal buoyancy.
Trace Elements: A term used to describe the many necessary elements in a marine aquarium, although usually in very small amounts. Among them are calcium, strontium, iodine and ozone (for purification).
Trickle Filter: A biological filtration system, which consists of, a plastic chamber with a biological filtration media. Water runs through the media, which mixes with the air, and reacts with the bacteria, which serve to remove ammonia and nitrites. It is this wet / dry exchange that promotes bacterial growth.
Tubercle: Small white pustules on the gill covers, which exists mainly on freshwater cyprinids.
Turbulence: Refers to how rapid and strong the water movement is.
Ultraviolet Sterilizer: A purification method, which uses ultraviolet light to kill harmful bacteria and microorganisms.
Under Gravel Filter (UGF): This type of filter involves a few long plastic tubes, which remain upright in the aquarium and are attached to a plate on the bottom. In each tube is an air stone attached to an air pump. As the air bubbles rise, a current is generated which continuously brings water from the aquarium, through the substrate and to the top of the tubes.
UV Sterilizer: A purification method, which uses ultraviolet light to kill harmful bacteria and microorganisms.
Ventral Surface: The bottom area of the fish.
Venturi: A popular protein skimmer design. It is a protein skimmer with a cylindrical body, used to draw air through a rapid current of water.
VHO Lighting: Very High Output fluorescent lighting. These lights are powered by special ballast, which deliver a wide spectra light.
Wet/Dry Filter: A biological filtration system, which consists of, a plastic chamber with a biological filtration media. Water runs through the media, which mixes with the air, and reacts with the bacteria, which serve to remove ammonia and nitrites. It is this wet / dry exchange that promotes bacterial growth.
Zeolite: An ammonia removing substance. It can only be used in freshwater tanks.