Results for “GH”

preterminal

Located slightly before the end or tip of something.

refractometer

Instrument used to measure salinity or specific gravity via the refractive index (basically, the degree that light bends when shined through something) of a liquid. Most models are designed to measure sodium chloride or brine solutions and not seawater which contains a more complex range of salts and minerals, but usually more accurate than a hydrometer nevertheless.

reverse osmosis

Form of purification, often abbreviated to RO, that removes dissolved salts and other impurities from water by applying pressure to it on one side of a semipermeable membrane. Pure water molecules are able to pass through the membrane while the majority of others are not, with more-or-less pure water the result. Sometimes used in combination with deionisation to remove additional mineral ions. Pure water can be harmful to fishes and is normally remineralised to some degree using proprietary products.

Used in 2 profiles

rift

Narrow fissure or zone of faulting formed via tensional stress in the earth's crust. When such forces are strong or prolonged enough to split the crust apart a central section will typically drop down or subside, sometimes forming a rift valley with steep walls as the gap widens. Water may become impounded in the valley, forming a rift lake.

Used in 5 profiles

rift lake

Type of lake that forms in a rift zone or rift valley and often very deep with steep cliffs around the margins, also known as a rift valley lake, sag pond, or fault-trough lake. The largest freshwater lakes in the world are all of this type. Also used in the aquarium hobby in reference to the Rift Valley lakes of the East African rift.

Used in 32 profiles

Rift Valley lake

Generic term for any lake formed in a rift valley, but often used in specific reference to a group located in the East African rift, particularly those lying in its western and southern sections, i.e., the African Great Lakes. In the aquarium hobby the meaning of the term is typically restricted even further to include just lakes Malawi, Tanganyika, and Victoria, the latter of which is not in fact a rift lake and is located in a shallow depression between the eastern and western branches of the main rift. These three lakes are famous for the high number of endemic fish species inhabiting them, especially members of the family Cichlidae.

river tank manifold

Home-made device used to achieve uni-directional flow in an aquarium when inhabitants naturally occur in high-velocity rivers and streams. Typically, one or more powerheads are located at one end of the aquarium with intakes at the opposite end, these being connected via pipework located under the substrate. Though certainly beneficial, this should not be considered an essential requirement in hill stream-type set-ups, however.

ruggose

Wrinkled, creased; having a rough surface.

saddle

Blotch-like marking extending over the dorsal surface in certain fishes. Highly variable in number and form depending on taxon, and often used as an identifying feature.

Used in 49 profiles

savanna

Type of grassland ecosystem characterised by any trees present being spaced in such a way that they do not form a closed canopy, thus sufficient light reaches the ground to support unbroken herbaceous cover consisting primarily of grasses. Also spelled 'savannah'.

Used in 10 profiles

school

Tightly-aggregated group of fishes, normally of the same species, which tends to orient and move in the same direction; the act of schooling. Often confused with shoal.

Used in 135 profiles

seine

Type of net designed to hang vertically in the water with the ends being manually drawn together to catch fishes, and which usually has weights at the lower edge and floats at the top; to fish with such a net.

silica sand

Sand containing a high concentration of silicon dioxide. Noted in aquaria for its purity, delicate appearance and lack of effect on water chemistry. Also known as silver sand.

specific epithet

In zoological nomencature, the second name in a binomen and in a trinomen. Has no nomenclatural function when used alone, though this is often done in aquarium literature or when referring to a species in passing if the genus being referred to is already clearly known. Also known as specific name.

Used in 24 profiles

speciose

Containing a high number of species. Normally applied to a taxonomic group or specified geographical area.

Used in 177 profiles

sponge filter

A basic air-powered filter which draws water through a sponge before returning it to the aquarium. Typically used in small aquaria where gentle water flow is required, or when raising fry.

Used in 277 profiles

stolon

A horizontal connection between organisms, e.g., the branching, stem-like structure seen in some lower animals and more commonly, higher plants.

streamlined

Contoured to reduce resistance to motion through a fluid.

Used in 10 profiles

subadult

An individual that has passed through the juvenile stage but not yet developed all adult characteristics, sexual maturity or size.

Used in 36 profiles

superior

In biology, located above or higher than.

Used in 2 profiles