Cavitation is the formation of vapour cavities in a liquid – i.e. small liquid-free zones ("bubbles" or "voids") –
that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid
changes of pressure that cause the formation of cavities where the pressure is relatively low. When subjected
to higher pressure, the voids implode and can generate an intense shockwave. When this happens inside a
closed external filter, you hear rumbling around the impeller and it causes stress and wear on the filter.
Chloramine (NH2Cl) is a chemical like ammonia with a chlorine atom instead of one of the hydrogen atoms.
It is used extensively in the treatment of domestic water supplies as a substitute for free chlorine that was used
in previous decades. Like chlorine, chloramine is poisonous to most aquatic organisms and must be removed
(or converted to something less toxic) with a “water conditioner” before tap water can be used in aquariums.
One of the breakdown products of chloramine is ammonia – which is also toxic- and is usually bound up as
ammonium (NH4) by aquarium water conditioners.
Cyprinid – a member of the large Family of fish (Cyprinidae) that includes the rasboras, danios, carps,
minnows and barbs. All the fish in this family are native to North America, Africa, and Eurasia. Cyprinids
have no stomach or teeth.
Cycling – is the process of establishing the bacterial colonies necessary for the breakdown of fish waste
(ammonia) to nitrates and then to less harmful nitrates. Usually done when an aquarium is first established by
introducing a small amount of fish waste (or another source of ammonia) and “seeding” the tank and filter with
a bacterial source from an established aquarium.
Flocculation is a chemical process where particles suspended in a fluid come together to form larger “flocs”
or flakes. Flocculation using aluminium sulphate (alum) is deliberately used in the treatment of domestic
water supplies to help remove impurities.
Free-swimming – refers to fry (baby fish) that have developed to a state where they can swim above the
substrate, after absorbing any yolk-sac left over from their development inside an egg.
Kelvin – a scale used to measure both absolute temperature and the colour of a light source (“light
temperature”). Color temperatures over 5,000K are called cool colors (blueish white), while lower color
temperatures (2,700–3,000 K) are called warm colors (yellowish white through red). Aquarium lighting is often
sold with a “K” rating – with very high values of up to 20,000K being valued for marine aquaria and medium
high values (6,500K to 10,000) being promoted as most suitable for aquatic plant growth. But K is just one
measure of the quality of light and full spectral data and intensity (power or radiant flux) are equally important.
Live Food – any animal food that is alive when eaten. This includes microscopic organisms (planaria, rotifers,
“infusoria”), small crustaceans (brine shrimp, daphnia) as well as many types of worm (vinegar eels,
microworm, grindal worm, white worm, blackworm, tubifex) and a range of both small and large organisms that
fish or invertebrates might eat (earthworms, crickets, fruitflies). Live food is recommended for conditioning of
most fish and sometimes as an essential part of the diet of some “difficult” species.
Melanotaenia (Latin genus name for many Australian rainbows) – from the Greek words melas=black and
tainia = band or stripe
Methylene Blue – a biological dye used to treat a range of aquarium diseases and conditions – notably fungal
diseases and as a disinfectant for fish eggs. Used as a component in many commercial “fish medicines”.
Rift Lake – most often used to refer to fish from one of the large African “rift” lakes – Malawi, Tanganyika and
Victoria. These lakes have unusual, highly alkaline, deep and rocky environments and have produced the
widest diversity of fish species of any freshwater environment. Unusually, cichlids occupy most niches
available to fish. These lakes are also home to many species of upside-down catfish (Synodontis).
Have you heard or read a word you think we should explain? – drop us a line via the CDAS website or forums