A

Actinic Lights: A type of florescent lighting with a high blue spectrum. It's the primary color of light in the ocean below 30 feet, required by corals and most reef creatures containing photosynthetic algae.

Activated Carbon: Carbon specially formulated for filtration. Carbon is good for removing a large number of toxins and other unwanted substances from aquarium water. It's useful for clearing or "cleaning" cloudy water. One problem with carbon is that is can release phosphate into the water, which stimulated algae growth.

Adipose Fin: The small fin located between the dorsal fin and the caudal fin. It seems to serve no purpose.

Algae: Underwater plant-like organisms. Some algae may resemble plants but they are not plants. Algae ranges in type from tall stalks of kelp to growths of green hair algae and encrusting growths of coralline algae.

Alkalinity: The capacity to buffer against pH drops. The greater the alkalinity, the more stable the pH will be and the less likely that there will pH swings. Alkalinity can be raised by adding a carbonate buffer material. Alkalinity can also be maintained through the use of substance called kalkwasser.

Ammonia: A toxic substance (NH3) that builds up in the aquarium. It is released by fish through their gills and as a result of waste buildup. Ammonia is the first step in the nitrogen cycle, and is removed by bacterial action where it is transformed into nitrite, or can be removed by mechanical filtration.

Amyloodinium ocellateum: Commonly called Oodinium, Marine Velvet, or Saltwater Ick. Signs of the disease are cloudy eyes, gasping for breath, listlessness, and white spots. Positive signs of the disease are gold or brown spots, rough skin, and rubbing against rocks, etc. Treatment can be done by a freshwater dip and copper (copper is very toxic to invertabrates).

Anaerobic: A lack of oxygen. Anaerobic zones in an aquarium are areas where no oxygen is present such as inside live rock or under sand or gravel. Anaerobic bacteria live in these areas where they transform nitrate into nitrogen gas. These areas can also produce hydrogen sulfide and other toxic substances.

Anal Fin: Single fin mounted vertically below the fish.

Anthocodia: the distal end of an octocoral polyp, usually the mouth and the 8 tentacles.

Anthostele: The lower part of the polyp, often stiffened, into which the distal portion of the polyp, the anthocodia is withdrawn.

Aragonite: A calcium-containing mineral usually found in the form of rock, gravel, or sand.

Asexual Reproduction: Asexual means having no sex or sex organs, therefore asexual reproduction would be reproducing by means other than sex.

B

Ballast: A power source required for fluorescent and metal halide lights. They are highly specialized and each type of light requires its own type of ballast.

Barbels: Barbels are the whisker-like appendages found on both sides of the mouth of all catfish.

Benthic/Benthos: Refers to living on or under the substrate at the bottom of the ocean.

Berlin System: A method of biological filtration that uses only live rock and a powerful protein skimmer.

Biological Filtration: A method of natural filtration that uses bacteria to break down waste substances by means of the nitrogen cycle. These include undergravel filters, trickle filters, and sponge filters.

Bivalve: A mollusk or other shelled animal who's shell is comprised of two separate halves, or valves, usually connected by a flexible hinge.

Bleaching: A process by which corals expel their colorful zooxanthellae and turn white or pale.

Brackish Water: It's neither freshwater nor saltwater; in nature this occurs at the mouths of rivers and swamps near the sea. Some fish live in saltwater but are spawned in brackish or freshwater and vice versa. There are several brackish species available in the aquarium hobby (brine shrimp prefer this sort of diluted salt water).

Brine Shrimp: A tiny species of shrimp growing to only about 1/4 inch. Also known as "Sea Monkeys", they are sold as a source of fish food. Brine shrimp make a delicious snack for reef fish, but are not very nutritious and should not be used as the sole food source.

Buffer: A substance added to the aquarium water to raise the alkalinity or adjust the pH. Several different types of buffering materials are available. Some can be used to raise or lower pH, and some can raise alkalinity without affecting pH.

Byssus Gland: A gland found in bivalve mollusks, such as clams. Producing fibrous threads that attach the animal to rocks. It is more of temporary attachment than permenant.

C

Calcareous: Any substance formed of or containing Calcium carbonate. It can help maintain a high pH in aquarium water.

Calcification: A process by which corals and coralline algae extract calcium from the seawater and deposit it in the form of calcium carbonate.

Calcium: A mineral that is the major building block of corals and other calcareous organisms. In a reef tank, calcium levels should be maintained between 380 and 480 mg/l. Calcium levels can be maintained through regular water changes, by using calcium additives, or through the use of kalkwasser.

Calcium Hydroxide: A substance mixed with water and dripped into the aquarium to maintain calcium "Ca(OH)2", pH, and alkalinity levels. See kalkwasser.

Cannister Filter: A filtration system that consists of an external cannister that contains various mechanical filtration media. Water is pumped out of the tank, forced through the cannister, and then returned to the tank.

Carapace: A bony or hard shell that covers part or all of an animal. Turtles, crabs, and boxfish are good examples.

Carbon: A substance used for filtration. See activated carbon.

Carnivore: Animals who hunt and eat other animals; a meat eater. Sharks are a good example.

Caudal Fin: The single fin mounted vertically at the rear of the fish. The tail fin.

Caulerpa: It's a fast growing attractive algae of which there are many variations with leaves that look like ferns, grapes, etc. Not surprisingly, the different types are named after the look of their leaves. All grow rapidly by sending out runners which are held in place by root like holdfasts.

Caudal Penduncle : The part of the body which attaches the caudal (tailfin) to the body. The surgeonfish's spines are located on the caudal penduncle.

Chemical Filtration: A method of filtration that uses chemical processes to clean the water. Examples of this type include activated carbon and protein skimmers.

Chiller: A piece of equipment used to cool down the water in an aquarium. Chillers are available in different types and sizes, including one that hooks up in-line with the water flow of the tank and one that drops into the sump. They all feature a thermostat for maintaining a constant temperature. Larger tanks require larger chiller units.

Chlorine: A substance used in municipal water supplies to kill bacteria. Chlorine is toxic to fish and invertebrates and must be removed from water before it can be added to the tank. A number of products are available for this purpose.

Cnidaria: A phylum of invertebrate animals comprising the sea anemones , corals , jellyfish , and hydroids.

Coelenterata: An aquatic animal of the Phylum Coelenterata which is characterized by a central mouth usually surrounded by tentacles bearing stinging cells, and no anus; includes sea anemones, corals, and jellyfish.

Coenenchyma: The tissue of a zoanthid that surrounds the polyps. Consists of mesoglea and may have sand imbedded in it.

Comensal: A relationship where two or more different kinds of animals live together and one benefits while the other does not.

Conspecific: Refers to animals of the same species.

Copper: A metal used in the form of copper sulphate to cure diseases and parasite infestations in the aquarium. Copper is highly toxic to marine invertebrates and should NEVER be used in a reef tank.

Corals: Are gastrovascular marine cnidarians (phylum Cnidaria; class Anthozoa) existing as small anemone-like polyps, typically forming colonies of many individuals.

Coralline Algae: An encrusting form of algae that forms calcareous crusts like coral. Coralline algae is very colorful, occurring in bright purple, pink and red colors. It is very desirable in the reef tank, and can be made to grow on rocks and other hard surfaces by maintaining optimum pH, alkalinity and calcium levels.

Crustaceans: A group of hard-shelled invertebrates that includes crabs and shrimps.

Cyanobacteria: Organisms that can form large colored mats. They are usually blue-green in color. Cyanobacteria is commonly referred to as red slime algae by hobbyists although it is not really an algae. It is a bacteria. Poor water quality with excessive nutrients are the usual causes. To combat, do frequent water changes, siphon out detritus, and use a good protein skimmer.

Cryptocaryon: A parasitic infection where white spots appear on the body and fins. Fish will scratch themselves against rocks and breathing may become rapid if gills are affected. Treatment can be done by copper or other anti-parasite remedies, but this is incompatible with invertabrates. Cleaner shrimps and wrasses will remove the parasites, but may not keep up with a major infestation. Cryptocaryon is often referred to as the marine equivalent of the freshwater white spot disease, Ichthyophthirius, or Ick.

D

Diatoms: An organism that commonly forms brown films on aquarium glass or rocks. Diatoms form their shells from silicate, and can be controlled to some degree by preventing the addition of this compound through the use of purified water.

Deionizer: A device for filtering water that uses several ion exchange resins to purify and remove impurities from the water.

Denitrification: The process by which nitrate is converted into nitrogen gas and released into the atmosphere. In the aquarium, denitrification is performed by anaerobic bacteria.

Detritus: Waste material that accumulated in gray piles in the aquarium. Detritus is high in nutrients and should be removed when possible to help prevent the growth of unwanted algae.

Detrivores: Animals that eat detritus. Common detritvores are urchins, stars, hermits, etc.

Dorsal Fin: The fin located on top of a fish. Most fish species have only one dorsal fin, but some will have two, one behind the other. Many species of clownfish will have two dorsal fins.

Dosing Pump: A device used to deliver small amounts of chemicals and trace elements into the aquarium water. It is recommended that kalkwasser be dosed in this manner.

E

Endemic Species: Species that naturally occurs in only one area or region. For example, the redfin darter is a fish endemic to the rivers of the Ozark forests.

F

Filter: Any device used to remove unwanted particles or compounds from aquarium water. Filters come in a variety of styles, but most fall into three main categories: biological, chemical, or mechanical.

Filter Feeder: An organism that filters out nutrients such as plankton, bacteria, or detritus from the water.

Filter Medium: Any substance used in water filtration systems to remove organic wastes and impurities from the water.

Fluidizing Bed: A method of biological filtration where water is forced through a cylinder containing small beads. Nitrifying bacteria growing on the beads removes waste materials from the water.

Foam Factionation: A method of removing proteins from water through the use of foam. This is the filtration method used by protein skimmers.

G

Genus: The (plural genera) is a grouping in the classification of living organisms having one or more related and morphologically similar species.

Gills: The membranes through which fish absorb dissolved oxygen from the water during respiration.

Gorgonian: A Gorgonian is a tropical or subtropical octocoral with upright branchy plant-like or fan-like growths and a skeleton made of a horny organic material. For example, the Sea Fans (Scientific names: Gorgonia ventalina, G. flabellum, G. mariae, Pacifigorgia spp.)

H

Halogen Lights: Lights with a very yellow color spectrum. Due to their color, these lights are not recommended for use in a reef aquarium.

Heater: A device used to heat the water in an aquarium. Heaters vary in size and style including drop-in types and submersible sump types. They feature an adjustable thermostat to maintain the water at a constant temperature. The size and wattage of a heater required will depend on the water volume of a tank.

Head and Lateral Line Erosion: Also known as hole-in-head disease and lateral line disease. A fish with this condition will develop holes in its' head and sometimes along its' lateral line. The main cause is nutritional deficiency, especially vitamin C. Stress and poor water quality also play a role. Untreated cases will cause disfiguring or death. To combat and cure, ensure good water quality and provide vitamin enriched foods, especially vitamin C.

Hemocyanin: A copper-containing protein with an oxygen-carrying function similar to that of hemoglobin, present in the blood of certain mollusks and arthropods.

Herbivore: An animal that eats plants. Herbivores such as snails and tangs are an important part of a reef tank because they help keep algae under control.

Hermatypic: Refers organisms that contain zooxanthellae. This usually means they need strong light to thrive.

Hermaphrodite: Refers to both male and female in the same organism.

Hydroid: A colonial coelenterates having the polyp phase dominant.

Hydrometer: An instrument used to determine the specific gravity of a fluid. Hobbyist grade hydrometers are temperature corrected to read the specific gravity at around 77°F (25°C) because specific gravity is temperature dependent.

I

Impeller: An electrically operated propeller that causes water to flow through a pump or filter.

Invertebrates: Animals with no backbones. This group includes mollusks, crustaceans, worms, corals, and composes a large number of reef inhabitants.

Iodine: A trace element found in seawater necessary in small quantities for some reef invertebrates, particularly corals and clams.

Ichthyophthirius: or Ick: see cryptocaryon.

J

Jellyfish: Any of a variety of free-swimming, marine invertebrates characterized by an umbrella-shaped body largely made up of a jelly-like substance and long, hanging tentacles with stinging cells on them.

K

Kalkwasser: The German word meaning calcium water, kalkwasser is a mixture of calcium hydroxide in water "Ca(HO)2". It is an extremely potent substance and should be used with caution. An overdose can raise alkalinity levels as high as 14 and can be harmful to animals.

L

Larvae: The first stage of development after hatching for many fish and invertebrates.

Lateral Line: A line of perforated scales along the side of a fish that is connected to a specialized organ used to sense vibrations in the water.

Live Rock: Rocks removed from the ocean that usually have a variety of sea life attached to them, including sponges, algae, coralline algae, worms, and starfish. Live rock is commonly used in reef aquariums because it contains bacteria that can help filter the water through nitrification.

Livebearer: A fish which gives birth to live young.

M

Macroalgae: Large plant-like algae commonly found in red, green and brown varieties. One of the most common of these is Caulerpa, which produces large green spheres resembling grapes.

Macroplankton: Usually refers to jellyfish, sargassum weed.

Microplankton: Usually refers to zooplankton and phytoplankton.

Mantle: Large, pigmented fleshy portion of tridacnid clams that is exposed to the light by gaping of the shell valves. Also called siphonal tissue. Also, the coral tissue in fleshy polyps (e.g. Catalaphyllia).

Mechanical Filtration: A water filtration method that uses filtering medium to remove particles from the water. Cannister filters, undergravel filters, and wet/dry filters are examples of mechanical filters.

Microalgae: Small microscopic types of algae such as the green algae and hair algae common in marine aquariums.

Metal Halide: A type of light bulb that uses special gases to give off a very bright white light. They give off a spectrum of light very similar to sunlight and are highly recommended for reef aquariums. Metal Halide bulbs require a special ballast unit for operation.

Mollusks: A group of soft-bodied invertebrates that includes snails, clams and squids. Most mollusks have some sort of hard external shell.

N

Nematocysts: Stinging mechanism used for defence and prey capture by Hydra and other members of the Cnidaria (Coelenterata). It is located within a specialised cell, the nematocyte consists of a capsule containing a coiled tube. When the nematocyte is triggered, the wall of the capsule changes its water permeability and the inrush of water causes the tube to evert explosively ejecting the nematocyst from the cell. The tube is commonly armed with barbs and may also contain toxin.

Nitrate: The final product in the nitrogen cycle (NO3). It is not toxic, but can be dangerous at high levels. Nitrate is created by the oxidation of nitrite by nitrobacteria. In a reef tank, nitrate levels should be kept below 10ppm.

Nitrification: The process by which bacteria converts ammonia into nitrite and then nitrite into nitrate. This is the basis of the nitrogen cycle.

Nitrite: The second product in the nitrogen cycle (NO2). Nitrite is a highly toxic substance that is produced by the oxidation of of ammonia by nitrosomonas bacteria. It is easily removed with biological filtration.

Nitrobacteria: The bacteria in a biological filtration system that converts nitrite into nitrate.

Nitrogen Cycle: The nitrogen cycle describes how wastes are broken down by bacteria in the aquarium. Animal waste breaks down into toxic ammonia (NH3). The ammonia id oxidized by nitrosomonas bacteria into nitrite (NO2), another highly toxic substance. Another bacteria called nitrobacteria oxidizes the nitrite into nitrate (NO3), a much less toxic substance. Some systems are capable of taking the process one step further, by using anaerobic bacteria to convert the nitrate into harmless nitrogen gas.

Nitrosomonas: The bacteria in a biological filtration system that converts ammonia into nitrite.

O

Octocoral: An octocoral has eight tentacles on each polyp. There are many different forms which may be soft, leathery, or even those producing hard skeletons.

Omnivore: Animals who eat both meat and vegetables, like Ocellaris Clownfish.

Osmolator: A device used to continuously replace evaporated water and maintain a constant specific gravity.

Osmosis: The process by which a liquid passes from an area of low concentration through a semi-permeable membrane to an area of high concentration.

Osmotic Stress: An adverse reaction caused when the salinity of an animal's environment changes drastically.

Ostracitoxin: The fish poison secreted into the water by fish of the genus Ostracion (Ostraciontidae).

Oxygen Reduction Potential (ORP): A simple measurement of the water's ability to cleanse itself.

Ozone: The very reactive form of oxygen which is commonly used in conjunction with a protein skimmer to enhance skimming and kill bacteria (O3). Ozone must be used carefully as too much can be toxic to fish and invertebrates.

Ozonizer: A device that uses high voltage electricity to produce ozone.

P

Parasite: An organism that feeds on the tissues of another organism. Parasites are one of the major causes of disease in aquarium fish.

Pectoral Fins: The anterior or uppermost of the paired fins, which correspond to the anterior limbs of the higher vertebrates.

Pelvic Fins: Paired fins behind or below the pectoral fins.

pH: A measure of the concentration of hydrogen and hydroxide ions. The pH of a solution measures how acidic or alkaline it is. pH values range from 0 to 14. A neutral solution has a pH of 7. A pH less than 7 indicates an acidic solution while a pH greater than 7 indicates an alkaline solution. pH can be regulated in the aquarium by using buffering materials. pH and alkalinity can also be maintained by the use of kalkwasser.

Phosphate: A nutrient that can case uncontrolled growth of algae in the aquarium. It can also be toxic in high concentrations and must be kept to a minimum in reef aquariums. Phosphate can be easily removed by a variety of commercial available filter media.

Photoperiod: The length of time that the aquarium lights are on.

Phytoplankton: Microscopic plants found drifting in seawater.

Plankton: Plankton are the drifters of the sea. Although they may have some form of locomotion they are mostly carried by water currents. Plankton is divided into macroplankton (jellyfish, sargassum weed) and microplankton, organisms that can only be seen by a microscope. The microplankton is divided into zooplankton, tiny marine animals, and phytoplankton, or plants. Most fish start their lives as small animals in the plankton..

Polyp: The living unit of a coral.

Powerhead: A small submersible pump commonly used inside an aquarium to provide additional water movement. Several powerheads can be used in conjunction with a controller unit to simulate natural wave actions.

Protein Skimmer: An external filtering device that uses air bubbles to remove nitrogen rich proteins, fatty acids, and other organic wastes. This is a required piece of equipment for maintaining good water quality in a marine aquarium.

Q

Quarantine: Isolation to prevent the spread of infectious disease.

R

Reactor: An isolated container, usually located near the sump, that performs a specific task such as increasing calcium or oxygen in the water.

Red Slime: See cyanobacteria.

Reverse Bohr Effect: The effect that occurs when lactate builds up in the blood of certain invertebrates and pH decreases, increasing the affinity of hemocyanin for oxygen

Redox: Reduction-oxidation potential. It is a measure of the ability of water to allow biological reactions to take place and is used as an indication of water quality. Redox can be measured with special electronic probes, and higher readings are better.

Reverse-flow Filtration: A biological filtration system where water is returned to the tank through the base instead of through the top.

Reverse Osmosis: A process for filtering water for use in an aquarium. This method works by forcing water under pressure through a special membrane. Reverse Osmosis (R/O) can produce very pure water, but it is a slow process and can only filter small amounts at a time.

S

Salinity: The number of grams of dissolved salt in 1,000gr of seawater , measured in parts per thousand (ppt). Natural seawater has a salinity of about 35 ppt.

Sessile: An organism that is not free to move about. It is usually permanently attached to a substrate of some kind. For example, a rock.

Silicone Sealant: A transparent, rubbery adhesive used in aquariums to bond glass and plug leaks. It can also be used in reef tanks to attach rock and coral formations.

Specific Gravity: The ratio of density of a given liquid to that of pure water. Specific gravity is used to measure the salinity of seawater as compared to distilled water. Distilled water has a specific gravity of 1.000 while natural seawater has a specific gravity of about 1.025.

Sponge Filters: A type of filter that provides both mechanical and biological filtration. As water passes through the sponge, particles are removed. Bacteria growing on the surface of the sponge also remove toxic substances from the water.

Strontium: A trace element found in seawater that is required for corals and creatures with calcareous skeletons to grow. Strontium levels can be maintained through regular water changes and by the use of strontium additives.

Substrate: The substance, base, or nutrient on which an organism grows.

Sump: The low area of water in an aquarium system. The sump is the reservoir below the dry section of a wet-dry or trickle filter. The water level in the sump varies with evaporation.

Sweeper Tentacles: Long stinging tentacles used by some aggressive hard corals to sting other nearby corals in order to obtain territory and growing space.

Syphon: A length of hose or tubing that uses gravity to move water from one location to another. Also, the organs used by some mollusks to inhale and exhale water.

Symbiotic: A phenomenon where two different organisms live together in a mutually beneficial relationship. Both organisms provide each other with food, protection, or some other need. The most famous example is the anemone and clownfish, where the anemone provides protection to the clownfish within its stinging tentacles, and the clownfish provides cleaning and scraps of food.

T

Trace Elements: A term used to describe the many necessary elements in a marine aquarium; these are elements that occur naturally in small quantities in seawater. These are required for survival by many reef organisms, and include calcium, iodine, strontium, molybdenum, lithium, and barium.

Trickle Filters: A biological filtration system which consists of a plastic chamber with a biological filtration media; this system drips water over some medium that is exposed to the air. The air helps to enhance the nitrification process. The filter medium usually consists of small plastic balls or strips of plastic.

Turnover: The rate of water flow through a filter. A high turnover rate is recommended for reef tanks.

U

Ultraplankton: Organisms that are less than 2 micrometers in size.

Ultraviolet Sterilizer(UV): A device that sterilizes water by passing it through a glass tube around an ultraviolet light. UV sterilizers can help remove bacteria, parasites, and algae spores from aquarium water. However, they can also remove some beneficial organisms from reef tanks.

Undergravel Filters: A filtration system that provides both mechanical and biological filtration. It consists of a plate that is placed underneath the gravel. Water is pulled down through the gravel where it is filtered and carried back up into the aquarium.

V

Venturi: A special type of valve that produces air bubbles by drawing air into a stream of water flowing under pressure. Venturi valves are used on a variety of protein skimmers.

VHO Lights: Very High Output (VHO) lights are specially designed fluorescent lights that give off a much higher intensity light than regular fluorescent bulbs. This makes them much more effective as light sources for reef systems, since many corals require strong light. As with all fluorescent lights, VHOs require a ballast unit for operation.

W

Water Change: The process of replacing a portion of aquarium water with a fresh saltwater mix. It's recommended that 20% to 25% of the water be changed each month in a reef tank.

Wet-dry Filter: A biological filtration system that is exposed to the air to aid nitrification. This system typically consists of a large box that is placed underneath the aquarium. Water passes down into the filter over a filtration medium where bacteria removes toxins. The water is then pumped back up into the tank. A sponge or other mechanical filtration medium may also be used in a wet/dry filter.

X

Y

Z

Zooplankton: Tiny microscopic animals found drifting in seawater. This includes the larval stages of many fish and invertebrates.

Zooxanthellae: Tiny plants that live in a symbiotic relationship with certain corals, clams, and some sponges. They receive nutrients from their host and provide a food source in return. It is the zooxanthellae that are responsible for the brilliant green, yellow, and blue colors in corals and clams.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z