It refers to the time of day in which a fish is active. Fishes can be day active or night active, and this influences their behaviour.

/əˈɡrɛʃ(ə)n/ /ɡreɪd/

It refers to the fact that some fishes can have a territorial and aggressive behaviour, that can be caused by stress factors in the environment, for example, territory, sex specific selection and genetic variation. There is no fish species who display invasive behaviour, in specificity, because every species can be aggressive sometimes depending on the surroundings.

In a community tank, aggressions are more likely to occur, as this type of aquarium is less respectful of the biologic needs of the species. The biotope aquarium, on the other hand, gives to each species its niche, as it can be divided in different sections, suited to each inhabitant. To lessen the risk of aggressive behaviours, the number of organisms should be proportional to the aquarium volume.

  • Peaceful: species that are overall peaceful, but can have aggressive behaviours, especially during breeding, courtship or parental care
  • Aggressive/ territorial: species that are likely to show aggressive behaviours towards specimen of the same or of another species
  • Predator: species that are predator by nature


Agriculture is the process of producing food, feed, fiber, and many other desired products by the cultivation of certain plants and the raising of domesticated animals (livestock).

Agriculture, which accounts for 70 percent of water abstractions worldwide, plays a major role in water pollution. Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. The resultant water pollution poses demonstrated risks to aquatic ecosystems, human health and productive activities (UNEP, 2016). So, directly or indirectly agriculture can have a direct impact on the water bodies it surrounds and on the existence of life forms that are found in the surrounding water.



Air temperature is a measure of how hot or cold the air is. It is the most commonly measured weather parameter. Air temperature affects the growth and reproduction of plants and animals, with warmer temperatures promoting biological growth. Air temperature also affects nearly all the other weather parameters. For instance, air temperature affects the rate of evaporation; relative humidity; wind speed and direction; precipitation patterns and types, such as whether it will rain, snow, or sleet.

Air temperature has a direct effect on the water temperature and is an interaction of natural environmental processes (e.g. air temperature, solar radiation, conduction from soil, etc.) and anthropogenic disturbances of the natural thermal regime, such as deforestation and hydroelectric development (Gras, 1969; Beschta et al.,1987; Benyahya et al., 2008). In recent years, a number of studies have identified global warming as another major influence of water temperature (Sinokrot et al., 1995; Webb, 1996; Mohseni et al., 1998, 1999; Pedersen and Sand-Jensen, 2007).

So, air temperature has a direct impact on water temperature that, in turn, affects dissolved oxygen, conductivity, oxidation reduction potential, pH, density, freshwater and saltwater temperature points, thermal stratification, pressure and water temperature points which govern the ice formation over water, and many other parameters, including compound toxicity (Source: So, all these factors influence the aquatic life.


A cold-blooded vertebrate animal of a class that comprises frogs, toads, newts, salamanders, and caecilians. They need water, or a moist environment, to survive and they are able to absorb water through their very thin skin. Some of them are toxic amphibians and are very brightly colored. Most amphibians’ larvae are aquatic and free-swimming—frogs and toads at this stage are called tadpoles. After a certain stage in their development, they develop limbs and lungs and some may eventually lose their tails. As adults, they will come out of the water and spend the rest of their lives on land.

Many of the frog species are in danger of extinction as they need certain environmental conditions to survive. Too much sun, dry wind and lack of humidity can damage their skin and dehydrate the animal.


Relating to, living in, or suited for both land and water. Something that can survive both in land and water.


Plants which germinate, flower and seed in one season or year, eg. button grass, fairy grass.  (See perennial plant).

/əˈkweəriəm/ /ˌdekəˈreɪʃ(ə)n/

Fish tank ornaments and decorations that can be added to your aquarium, like driftwood, leaves, stones, snails, caves for the underwater natural appeal and to create a place for fish to hide and play.


Size of the aquarium, length, width and height, or often height and diameter. These are either in inches or cm. They are used to calculate the volume of the aquarium. The volume of water that the aquarium can hold will be always less or equal to the volume of the aquarium. See aquarium volume for more information.


Equipment used in an aquarium, like air pumps and accessories, chillers, cleaning equipment, CO2 equipment, dosing pumps filter cartridges & material, aquarium heaters , lighting, media reactors, overflow boxes, planting tools, protein skimmers, pumps, reef scaping equipment, reverse osmosis, testing kits & equipment, UV sterilizers, wave makers and many more.


The Volume of the Aquarium, the amount of space that the Aquarium occupies, or that is enclosed within it. Most of the Aquariums are rectangular, many square and a few cylindrical, but you may still get an odd-shaped aquarium. The volume of an aquarium can be calculated based on its shape. The volume of aquarium water also determines the number of fishes of a particular size that can be kept in the aquarium.

Rectangular Aquariums

  • Length  (inches) or  (cm) x Width  –  (inches) or (cm) Height – (inches) or (cm)
  • If in cm or any metric system, convert volume to Litres
  • If in Inches or any imperial (UK) convert volume to Gallons


  • The cube-shaped aquarium has the easiest volume equation – simply raise the edge length to the power of three: cube = length³ (in inches or cm)

Cylindrical Aquariums 

  • cylinder = π * (diameter / 2)² * height (in inches or cm)
  • π = pi is approximately 3.14
  • If your fish tank is a half-cylinder divide the formula above by 2


Quick Conversions:

  • 1 inch = 2.54cm
  • 1 cubic cm = 0.001 litres
  • 1 Cubic Inch = 0.004329 US Gallon
  • 1 Cubic Inch = 0.00360465 UK Imperial Gallon
  • 1 US Gallon = 3.78541 litres
  • 1 UK Imperial Gallon = 4.54609 litres
  • Temp = (32°F − 32) × 5/9 = 0°C
  • (F= Fahrenheit) (C=Celsius)


An aquatic biotope is described as an environment or a natural area where a set of specific collections of living beings, including that of plants and animals, coexist.

Ernst Haeckel (1834-1919), a German zoologist, first described the concept of biotope where he described how one ecosystem, its biota or living beings are shaped by environmental factors (such as water, soil, and geographical features) and by the relationships that each of these living beings have.


Aquatic plants are plants that live and survive in aquatic environments either freshwater, brackish or saltwater. They can be classified as hydrophytes or macrophytes. Hydrophytic plants grow in water or in soil that is consistently wet. Examples of hydrophyte habitats include fresh or salt water marshes, savannahs, bays, swamps, ponds, lakes, bogs, fens, quiet streams, tidal flats and estuaries.

A macrophyte is an aquatic plant that grows on the shore line, on the banks or in the water and is either emergent, submergent, or floating. Macrophytes need specific substrates to grow and provide unique habitats for other organisms. Macrophytes thrive in areas where there is a mixture of sand and muck, which is a semifluid, fine-grained, organic-rich sediment. They are also found in conditions that are optimal for upwelling along the coast when winds blow along the shore.

Macrophytes can modify the microclimate within the littoral zone by reducing the effects of waves and the creation of thermal gradients that prevent water from mixing. This, in turn, has effects on the nutrient availability and on the diffusion of oxygen through the sediment, and it also contributes to the nutrient cycling in the littoral zone. This creates a very positive environment for aquatic animals from the point of view of their growth, development and natural sustainability.

/ əˈkwatɪk/ /ˌvɛdʒᵻˈteɪʃn/

Consists of any kind of vegetation that lives near to or in the water. It includes aquatic grasses, mosses, algae, and aquatic plants. They provide important ecologic functions essential for the aquatic habitats, their water quality, and their fauna.


The tiny animals and plants that encrust hard substrates, such as rocks, in aquatic environments. “Aufwuchs” in German refers to “surface growth” or “overgrowth” of parts of rooted plants, both of marine and freshwater environments, for example algae –especially green algae and diatoms – make up the dominant component of aufwuchs communities. Many tiny small crustaceans, protozoans’ rotifers, larvae are part of the freshwater aufwuchs faunas. Aufwuchs are source of food for many fishes, like hill stream loaches, gobies, cichlids etc. and they have adopted to use Aufwuchs as a natural food source.


The Biotope Aquarium Contest is a competition organized by the Biotope Aquarium Project that can be entered by any aquarium enthusiast, following the directories available on the site. The competitions have been taking place since 2016, both online and with a final contest live, where aquarists are able to show their skills and biotope correct aquariums.

Check out guidelines and instruction to submit and participate.

BIOTOPE AQUARIUM Model is an authentic re-construction of the original – often of a very small – aquatic biotope, which might disappear at any time without warning, or has already vanished. This little piece of Nature benefits the well-being of the aquarium inhabitants if:

  • simulates BIOTOPE In NATURE
  • replicates conditions of lake, creek or river
  • has correct water type and chemical parameters
  • provides a living space for the correct biological community
  • applies the correct décor material

BAP Map or BIOTOPE AQUARIUM Project Map is the main instrument of the biotope mapping offered to beginners and experienced aquarists to build their own BIOTOPE AQUARIUM Model. Geographic map marks the GPS locations with the detailed aquatic biotope research and data on aquatic inhabitants that includes:


It is benthopelagic a species that lives and feeds near or at the bottom of a watercourse, as well as in midwaters or near the surface. These species feed on benthic as well as free swimming organisms.


The section dedicated to the presentation of biotopes in the environment. Each page introduces a biotope in nature, giving information about the location, the inhabitants, the aquatic vegetation, the water chemistry, the substrate, the aquatic biotope and the environment. Each page is completed with photos and videos.


Biocoenosis refers to the indeendent organisms that live together in a specific habitat, biotope, or ecosystem interacting with one another and forming an ecological, closely integrated community. An ecological community can also be called a biocoenosis.


Also called biological diversity, it indicates the variety of extant species in the environment and also encompasses the genetic variability within the species that form biological communities.


A group of diverse species that occupy the same specific area and interact with each other. The overall structure of a community is determined by the diversity, the abundance and the specific interactions among the species within it.


From Greek bios (“life” or “organism”) and topos (“place”). A biotope is a limited area of uniform environmental conditions that provides living space for several organisms that coexist, interact, and cooperate, thus forming a biological community. Biotopes and the communities they host make up ecosystems that change constantly because of abiotic and biotic factors, but which are, nowadays, often threatened by human activity.


A biotope aquarium is an aquarium that replicates the natural biotope and ecosystem, where aquatic organisms, especially those threatened in the environment, can survive and adapt to a new home. For a biotope aquarium to be correct and replicating exactly the original habitat of the living species, organisms, environmental elements and conditions need to be selected accurately.


Carnivorous fish have a meat-based diet which can include insects, other fish, and other invertebrates. They usually have different body structures, for example they can have a larger mouth, larger teeth and a more aerodynamic body for quickly swimming through the water. Some carnivorous fish are active hunters that will chase down their preys, like sharks; others wait for the prey to come to them, also in the deepest parts of the ocean. Some other species, like catfish or loach, resort to scavenging and catch all the food that has sunk to the bottom.

Common carnivorous aquarium fishes are some types of cichlid, arrowana, and piranhas. They should be regularly offered live food and frozen food, like feeder fish, brine shrimp, mosquito larvae, worms, mollusks, and other invertebrates.

CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) is a global agreement among governments, adopted in 1975 in order to regulate or ban international trade in plant or animal species that are under threat and safeguard their survival.


The presence of sediments in the water can be measured: the ratio of the dry sediment in a mixture of water and sediments/ the total weight of the mixture.

Waters with a high concentration of sediments are usually turbid.


The capability of a fluid – in our case water – to conduct electricity and let an electrical flow pass through it. It is strictly linked to the concentration of ions, that result from various minerals and inorganic materials dissolved in the fluid. The more ions are present, the more conductive is the fluid.

/dɪˈzɒlvd/ /ˈɒksᵻdʒ(ə)n/

It measures how much oxygen is found in the water. The presence of oxygen in the water is a positive indicator of quality, while its absence could be a sign of pollution. Sources of dissolved oxygen can be atmosphere, aeration and photosynthesis from algae and aquatic plants.


The tallest plant species present at a site.  There must be several individuals of the same plant present at one site for it to be the dominant species.

/ˈdreɪnɪdʒ/ /ˈbeɪs(ə)n/

Region or catchment area that includes all the minor, superficial watercourses that funnel and pour in the main river. The drainage basin acts as a collector of the precipitations which flow to a single or more streams, including the water of the main watercourse and its tributaries.


The study of relationships between living organisms and their environment.


An ecosystem is a biological system that consists of different organisms, interacting which each other, and their physical environment. Every biotic (living) and abiotic (non-living) component of the ecosystem contribute to make it function as a unit. Nature is made of different units; thus, of different ecosystems.

An ecosystem is based on an ecological community made of different populations of different organisms which live and work together in a particular environment or habitat.


Water hardness is caused by the presence of calcium and magnesium ions and it indicates the capacity to precipitate soaps, that deposits on the bottom of the solution. Water is, thus, categorized in hard, medium, or soft water. Groundwater tends to be harder, while surface water is generally softer.


The place in which an organism or a community or organisms live and grow, including all factors and conditions of the surrounding environment that the organisms need in order to survive. The main components of a habitat include space, shelter, water, and food in the correct amount for each species.


Invasive Alien Species (IAS) are living organisms, including animals and plants, introduced accidentally or deliberately into a geographical area different from that of their origin, with serious negative consequences for the new environment. They represent a major threat to native plants and animals worldwide and cause damage worth billions of euros to the global economy every year.


An invertebrate is an animal that lacks a vertebral column and, thus, does not belong to the chordate subphylum Vertebrata. Generally, invertebrate animals are soft-bodied, lacking a rigid internal skeleton for the attachment of muscles. Some of them, however, possess a hard outer skeleton that protects the body.

Invertebrates make up more than the 90% of all living animal species, such as sea stars, sea urchins, earthworms, sponges, jellyfish, lobsters, crabs, insects, spiders, snails, clams, and squid.

IUCN (International Union for Conservation of Nature and Natural Resources) is an organization founded in 1948 whose aim is to influence, encourage, and assist societies to conserve the integrity and diversity of nature,and ensure that any use of natural resources is equitable and ecologically sustainable.

IUCN has drafted a Red List Categories and Criteria that is intended to be an easily and widely understood system for classifying species at high risk of global extinction. Species are divided into the followng categories:

  • Not Evaluated (N/E);
  • Data Deficient (DD): a taxon about which there is no adequate information to make an assessment about its endangerment;
  • Least Concern (LC): a taxon that does not qualify as endangered;
  • Near Threatened (NT): a taxon close to qualifying for a threatened category;
  • Vulnerable (VU): taxons considered to be facing high risk of extinction in the wild;
  • Endangered (EN): a taxon considered to be facing a very high risk of extinction in the wild;
  • Critically Endangered (CR): a taxon considered to be facing an extremely high risk of extinction in the wild;
  • Extinct in the Wild (EW): a taxon known to survive in cultuvation, captivity or as a neutralised population well outside the past range. A taxon is presumed EW when surveys in the wild have failed to record it;
  • Extinct (EX): a taxon which surveys have failed to record.


Carbonate hardness is the measure of the alkalinity of water, determined by the presence of carbonates of calcium. Carbonate hardness is related to the ability of water to maintain a stable environment and a stable pH.


With regard to the forms in the sections BAM, FISH, and PLANT, it refers to the level of complexity to decorate the biotope tank, find the species and décor material in the general aquarium shops and manage a species in a biotope correct aquarium. Ratings are: easy, medium or difficult.


Marine, or saltwater fish are all those fish species that live in the ocean, where they either live alone or form schools. Different marine fish species live in different marine habitats, that can largely vary in terms of salinity and alkalinity levels, temperature, and pH values.

Marine fish species are commonly kept in home aquaria and they are constantly threatened by the fish industry.


Collection and comparison of information to determine type, extent and cause of change.


In biology, a genus or species with only one type of representative. A monotypic taxon is a taxonomic group that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or infraspecific taxa. In the case of genera, the term “unispecific” or “monospecific” is preferred.


An ornamental fish is a fish that is kept in home aquarium for aesthetic purposes. There are a lot of different fish species that are considered ornamental and that can be included in home aquaria; they encompass a wide variety of species, of many shapes, sizes, and colours.


It is perennial any plant that persists and grows for several years, across the seasons. Usually, they are plants which complrete their life cycle in more than two years. As they grow, they start to bloom and bear fruits in spring and summer, while they are quiescent in autumn and winter. Every year they return active in spring, so that their life cycles can continue over a long period of time.


A plant whose life cycle extends for more than two years (e.g. bladder saltbush).  Some perennials, such as grasses and herbs, have above-ground parts, which die off in unfavorable seasons leaving an underground structure, such as a bulb or rhizome, to produce new growth when the season is favourable, (e.g. Mitchell grass). (See annual plant).

Scale indicative of the acidity or basicity of a substance, that is influenced by minerals and dissolved materials. A substance is acid when its pH ranks between 0 and 5,5 and basic, or alkaline, when its pH is between 7,5 and 14. When the pH is between 5,5 and 7,5, a substance is considered neutral.


Plantlets are young or small plants that can grow or be produced on the margins of the plant itself as a form of asexual reproduction.


Plant litter refers to the dead plant material, such as leaves, bark, needles and twigs that have fallen on the ground or in the water. It makes up debris or organic material whose constituents add to the soil or water. It is an important factor for the dynamics of an ecosystem.

/rʌɪˈpɛːrɪən/ /zəʊn/

The area between land and a watercourse, characterized by the presence of many aquatic plants and other vegetation that can grow to create ana actual forest on the banks of a river. The riparian zone is important for the wellness and the protection of the aquatic environment.


A riverbed is the bed or the channel in which a river flows and that is shaped by the flowing water. A riverbed can be more or less wide, from a few feet to a thousand metres. Nevertheless, from time to time a riverbed might not contain flowing water or be dry all the same. This particularly happens in regions of the world where dry and rain season alternate. Furthermore, riverbeds can consists of different materials, such as rock, sand, clay, silt, or other unconsolidated materials resulting from earlier deposition.


Area of land around a river or another water body that is collected in that area because of the conformation of the landscape. All the water that is collected in the same catchment area eventually flows together in the same water body.


Having, resmbling, or being a rhizome.

A rhizome is a horizontal underground plant stem, which is able to produce the shoot and root systems of a new plant. These stems allow a parent plant to produce offrispring through asexual reproduction, that is, propagation, and to survive in adverse condition. The rhizomes perform several functions that help the growth of the plant, such as storing food and save nutrients (proteins, carbohydrates, minerals).


It refers to climates or regions which lack sufficient rainfall for regular crop production.  Usually defined as a climate with annual rainfall greater than 250 mm but less than 375 mm.


The detachment and transportation of soil and its deposition at another site by wind, water or gravitational effects.

Natural erosion: erosion occurring under natural environmental conditions, undisturbed by humans.

Accelerated erosion: erosion which is attributable to the influence of human activities.  See also scald, hummockingand pedestalling.

Water erosion: an erosion process in which soil is detached and transported from the land by the action of rainfall,  runoff and seepage.  Types of water erosion include:

  • Splash erosion: the spattering of soil particles caused by the impact of raindrops on the soil; an important component of sheet erosion.
  • Sheet erosion: the removal of a fairly uniform layer of soil from the land surface by wind and raindrop splash and /or runoff. No rills are formed.
  • Rill erosion: the removal of runoff from the land surface whereby numerous small channels are formed.  Rills are defined as small channels up to 30 cm deep.
  • Gully erosion: the removal of soil by water whereby large incised channels (> 30 cm deep) are formed.  The severity of gully erosion may be recorded as minor, moderate, severe or very severe.  Gully erosion processes may include the removal of soil from the land surface by concentrated runoff or the dispersion of unstable subsoils.
  • Stream bank erosion: the removal of soil from stream banks by the direct action of steam flow and/or wind /wave action. Typically occurs during periods of high flow.
  • Wind erosion: the removal and transportation of soil by wind. (See sheet erosion)


In the aquarium, the substrate corresponds to the materials used in the tank that should replicate the natural substrate and natural conditions for the species.


The surface on which an organism lives. Regarding rivers, the substrate corresponds to its bottom, its constituents and sediments. The substrate can affect the biodiversity of a watercourse.


With regard to water, it refers to the fact that it is motionless and still. Stagnant water can be confined, standing, experiencing a low flow or usage.

Because of its poor quality or shallow depth, stagnant water is unusable.


Also called tannic acid, tanin is a yellowish or brownish, bitter organic compound which can be present in roots, wood, bark, leaves, fruit, and other plant tissues. It consists of some derivatives of gallic acid and it a deterrent to herbivores.


A water body consist in an accumulation of water. Water bodies are classified in different categories on the basis of their size: oceans (further divided in seas), inland bodies of water (as lakes), bodies of water in motion (as rivers, streams, etc.), frozen water bodies.


It refers to a more specific part of the interested water body, which is thus further divided in upper, medium, and lower body part.


With regard to the different sections of the BIOTOPE AQUARIUM Project, the category “Water Chemistry” groups all the information about the condition of water in the given biotope or in the Biotope Aquarium Model.

Under “Water Chemistry” are listed some information and the chemical parameters of the described watercourse. It lists the water type, water colour, water transparency, the concentration of sediments, water temperature, water flow/current, pH, conductivity, GH, KH, and dissolved oxygen.


Colour is one of the organolectic properties of water. Its colour varies with its physical, chemical and bacteriological conditions. Colour can distinguish water in:

  • Clear water: typical of water courses with a good flow. It appears clear and of a greenish colour. The pH is usually neutral or slightly acidic, the conductivity and the presence of dissolved materials is low,
  • Black water: typical of water courses with a slow or no flow. It appears of a dark colour because of the tannins resulting from the decay of the vegetation. The pH is usually acidic and the conductivity low,
  • White water: typical of water bodies that contain high levels of suspended sediments. The pH is usually neutral and the conductivity high,
  • Mixed water: typical of water bodies that go through different environments, so that the water changes properties in the different parts of its course.

/əˈbʌv/ /ˈwɔːtəfɔːl/

A waterfall is an area where water flows over a vertical drop or a series of steep drops in the course of a stream or river.

A waterfall is a part of the river or other water bodies and it is caused by the water’s steep fall over a rocky ledge into a plunge pool below. Waterfalls are also called cascades. The process of erosion, the wearing away of earth, plays an important part in the formation of waterfalls.

A waterfall acts as a natural barrier that many fish species cannot cross. That is the reason why the fish fauna above waterfall might be different from the fish fauna below the waterfall, especially if influenced by tides, like it often happens on the islands of Papua New Guinea. An exception to this is represented by a few fish species who can climb up the waterfall with special adhesive organs, like a few gobies or Balitoridae that uses its suctioning mouth and/or a sucker on its stomach to inch upward against the flow of water.


Water bodies usually have currents, that can be distinguished in surface currents and deep-water currents. When talking about a river, its flow can be lower or higher and determines how and how much water flows. Current is determined by many different factors, among which winds, gravity, water volume, riverbed conformation, etc.

/ˈwɔːtə/ /trɑːnsˈparənsi/

Water transparency is linked to the presence of particles suspended in the water and to the amount of light and sun radiations that can penetrate it and at what depth. The more transparent the water, the deeply sunlight can penetrate, thus enabling plants and organisms on the bottom to survive.


Water is divided in four different types: meteoric water, from rain or snow, surface water, further distinguished in freshwater, brackish water and salt water, and telluric water, as that from springs or aquifers.